ReportWire

Tag: Evolution and Darwin

  • Evolution of uniquely human DNA was a balancing act, study concludes

    Evolution of uniquely human DNA was a balancing act, study concludes

    [ad_1]

    Newswise — SAN FRANCISCO, CA—January 13, 2023—Humans and chimpanzees differ in only one percent of their DNA. Human accelerated regions (HARs) are parts of the genome with an unexpected amount of these differences. HARs were stable in mammals for millennia but quickly changed in early humans. Scientists have long wondered why these bits of DNA changed so much, and how the variations set humans apart from other primates.

    Now, researchers at Gladstone Institutes have analyzed thousands of human and chimpanzee HARs and discovered that many of the changes that accumulated during human evolution had opposing effects from each other.

    “This helps answer a longstanding question about why HARs evolved so quickly after being frozen for millions of years,” says Katie Pollard, PhD, director of the Gladstone Institute of Data Science and Biotechnology and lead author of the new study published today in Neuron. “An initial variation in a HAR might have turned up its activity too much, and then it needed to be turned down.”

    The findings, she says, have implications for understanding human evolution. In addition—because she and her team discovered that many HARs play roles in brain development—the study suggests that variations in human HARs could predispose people to psychiatric disease.

    “These results required cutting-edge machine learning tools to integrate dozens of novel datasets generated by our team, providing a new lens to examine the evolution of HAR variants,” says Sean Whalen, PhD, first author of the study and senior staff research scientist in Pollard’s lab.

    Enabled by Machine Learning

    Pollard discovered HARs in 2006 when comparing the human and chimpanzee genomes. While these stretches of DNA are nearly identical among all humans, they differ between humans and other mammals. Pollard’s lab went on to show that the vast majority of HARs are not genes, but enhancers— regulatory regions of the genome that control the activity of genes.

    More recently, Pollard’s group wanted to study how human HARs differ from chimpanzee HARs in their enhancer function. In the past, this would have required testing HARs one at a time in mice, using a system that stains tissues when a HAR is active.

    Instead, Whalen input hundreds of known human brain enhancers, and hundreds of other non-enhancer sequences, into a computer program so that it could identify patterns that predicted whether any given stretch of DNA was an enhancer. Then he used the model to predict that a third of HARs control brain development.

    “Basically, the computer was able to learn the signatures of brain enhancers,” says Whalen.

    Knowing that each HAR has multiple differences between humans and chimpanzees, Pollard and her team questioned how individual variants in a HAR impacted its enhancer strength. For instance, if eight nucleotides of DNA differed between a chimpanzee and human HAR, did all eight have the same effect, either making the enhancer stronger or weaker?

    “We’ve wondered for a long time if all the variants in HARs were required for it to function differently in humans, or if some changes were just hitchhiking along for the ride with more important ones,” says Pollard, who is also chief of the division of bioinformatics in the Department of Epidemiology and Biostatistics at UC San Francisco (UCSF), as well as a Chan Zuckerberg Biohub investigator.

    To test this, Whalen applied a second machine learning model, which was originally designed to determine if DNA differences from person to person affect enhancer activity. The computer predicted that 43 percent of HARs contain two or more variants with large opposing effects: some variants in a given HAR made it a stronger enhancer, while other changes made the HAR a weaker enhancer.

    This result surprised the team, who had expected that all changes would push the enhancer in the same direction, or that some “hitchhiker” changes would have no impact on the enhancer at all.

    Measuring HAR Strength

    To validate this compelling prediction, Pollard collaborated with the laboratories of Nadav Ahituv, PhD, and Alex Pollen, PhD, at UCSF. The researchers fused each HAR to a small DNA barcode. Each time a HAR was active, enhancing the expression of a gene, the barcode was transcribed into a piece of RNA. Then, the researchers used RNA sequencing technology to analyze how much of that barcode was present in any cell—indicating how active the HAR had been in that cell.

    “This method is much more quantitative because we have exact barcode counts instead of microscopy images,” says Ahituv. “It’s also much higher throughput; we can look at hundreds of HARs in a single experiment.”

    When the group carried out their lab experiments on over 700 HARs in precursors to human and chimpanzee brain cells, the data mimicked what the machine learning algorithms had predicted.

    “We might not have discovered human HAR variants with opposing effects at all if the machine learning model hadn’t produced these startling predictions,” said Pollard.

    Implications for Understanding Psychiatric Disease

    The idea that HAR variants played tug-of-war over enhancer levels fits in well with a theory that has already been proposed about human evolution: that the advanced cognition in our species is also what has given us psychiatric diseases.

    “What this kind of pattern indicates is something called compensatory evolution,” says Pollard. “A large change was made in an enhancer, but maybe it was too much and led to harmful side effects, so the change was tuned back down over time—that’s why we see opposing effects.”

    If initial changes to HARs led to increased cognition, perhaps subsequent compensatory changes helped tune back down the risk of psychiatric diseases, Pollard speculates. Her data, she adds, can’t directly prove or disprove that idea. But in the future, a better understanding of how HARs contribute to psychiatric disease could not only shed light on evolution, but on new treatments for these diseases.

    “We can never wind the clock back and know exactly what happened in evolution,” says Pollard. “But we can use all these scientific techniques to simulate what might have happened and identify which DNA changes are most likely to explain unique aspects of the human brain, including its propensity for psychiatric disease.”

    ###

    About the Study

    The paper “Machine learning dissection of human accelerated regions in primate neurodevelopment,” was published in the journal Neuron on January 13, 2023.

    Other authors are Kathleen Keough, Alex Williams, Md. Abu Hassan Samee, and Sean Thomas of Gladstone; Fumitaka Inoue, Hane Ryu, Tyler Fair, Eirene Markenscoff-Papadimitrious, Beatriz Alvarado, Orry Elor, Dianne Laboy Cintron, Erik Ullian, Arnold Kriegstein, and John Rubenstein of UC San Francisco; Martin Kircher, Beth Martin, and Jay Shendure of University of Washington; and Robert Krencik of Houston Methodist Research Institute.

    The work was supported by the Schmidt Futures Foundation and the National Institutes of Health (DP2MH122400-01, R35NS097305, FHG011569A, R01MH109907, U01MH116438, UM1HG009408, UM1HG011966, 2R01NS099099).

    About Gladstone Institutes

    To ensure our work does the greatest good, Gladstone Institutes focuses on conditions with profound medical, economic, and social impact—unsolved diseases. Gladstone is an independent, nonprofit life science research organization that uses visionary science and technology to overcome disease. It has an academic affiliation with the University of California, San Francisco.

    [ad_2]

    Gladstone Institutes

    Source link

  • Study reveals average age at conception for men versus women over past 250,000 years

    Study reveals average age at conception for men versus women over past 250,000 years

    [ad_1]

    Newswise — BLOOMINGTON, Ind. — The length of a specific generation can tell us a lot about the biology and social organization of humans. Now, researchers at Indiana University can determine the average age that women and men had children throughout human evolutionary history with a new method they developed using DNA mutations.

    The researchers said this work can help us understand the environmental challenges experienced by our ancestors and may also help us in predicting the effects of future environmental change on human societies.

    “Through our research on modern humans, we noticed that we could predict the age at which people had children from the types of DNA mutations they left to their children,” said study co-author Matthew Hahn, Distinguished Professor of biology in the College of Arts and Sciences and of computer science in the Luddy School of Informatics, Computing and Engineering at IU Bloomington. “We then applied this model to our human ancestors to determine what age our ancestors procreated.”

    According to the study, published today in Science Advances and co-authored by IU post-doctoral researcher Richard Wang, the average age that humans had children throughout the past 250,000 years is 26.9. Furthermore, fathers were consistently older, at 30.7 years on average, than mothers, at 23.2 years on average, but the age gap has shrunk in the past 5,000 years, with the study’s most recent estimates of maternal age averaging 26.4 years. The shrinking gap seems to largely be due to mothers having children at older ages.

    Other than the recent uptick in maternal age at childbirth, the researchers found that parental age has not increased steadily from the past and may have dipped around 10,000 years ago because of population growth coinciding with the rise of civilization.

    “These mutations from the past accumulate with every generation and exist in humans today,” Wang said. “We can now identify these mutations, see how they differ between male and female parents, and how they change as a function of parental age.”

    Children’s DNA inherited from their parents contains roughly 25 to 75 new mutations, which allows scientists to compare the parents and offspring, and then to classify the kind of mutation that occurred. When looking at mutations in thousands of children, IU researchers noticed a pattern: The kinds of mutations that children get depend on the ages of the mother and the father.

    Previous genetic approaches to determining historical generation times relied on the compounding effects of either recombination or mutation of modern human DNA sequence divergence from ancient samples. But the results were averaged across both males and females and across the past 40,000 to 45,000 years.

    Hahn, Wang and their co-authors built a model that uses de novo mutations — a genetic alteration that is present for the first time in one family member as a result of a variant or mutation in a germ cell of one of the parents or that arises in the fertilized egg during early embryogenesis — to separately estimate the male and female generation times at many different points throughout the past 250,000 years.

    The researchers were not originally seeking to understand the relationship of gender and age at conception over time; they were conducting a broader investigation about the number of mutations passed from parents to children. They only noticed the age-based mutation patterns while seeking to understand differences and similarities between these pattens in humans versus other mammals, such as cats, bears and macaques.

    “The story of human history is pieced together from a diverse set of sources: written records, archaeological findings, fossils, etc.,” Wang said. “Our genomes, the DNA found in every one of our cells, offer a kind of manuscript of human evolutionary history. The findings from our genetic analysis confirm some things we knew from other sources (such as the recent rise in parental age), but also offer a richer understanding of the demography of ancient humans. These findings contribute to a better understanding of our shared history.”

    Additional contributors to this research were Samer I. Al-Saffar, a graduate student at IU at the time of the study, and Jeffrey Rogers of the Baylor College of Medicine.

    [ad_2]

    Indiana University

    Source link

  • Shedding light on the origin of complex life forms

    Shedding light on the origin of complex life forms

    [ad_1]

    How did the complex organisms on Earth arise? This is one of the big open questions in biology. A collaboration between the working groups of Christa Schleper at the University of Vienna and Martin Pilhofer at ETH Zurich has come a step closer to the answer. The researchers succeeded in cultivating a special archaeon and characterizing it more precisely using microscopic methods. This member of the Asgard archaea exhibits unique cellular characteristics and may represent an evolutionary “missing link” to more complex life forms such as animals and plants. The study was recently published in the journal “Nature”.

    All life forms on earth are divided into three major domains: eukaryotes, bacteria and archaea. Eukaryotes include the groups of animals, plants and fungi. Their cells are usually much larger and, at first glance, more complex than the cells of bacteria and archaea. The genetic material of eukaryotes, for example, is packaged in a cell nucleus and the cells also have a large number of other compartments. Cell shape and transport within the eukaryotic cell are also based on an extensive cytoskeleton. But how did the evolutionary leap to such complex eukaryotic cells come about? Most current models assume that archaea and bacteria played a central role in the evolution of eukaryotes. A eukaryotic primordial cell is believed to have evolved from a close symbiosis between archaea and bacteria about two billion years ago. In 2015, genomic studies of deep-sea environmental samples discovered the group of the so-called “Asgard archaea”, which in the tree of life represent the closest relatives of eukaryotes. The first images of Asgard cells were published in 2020 from enrichment cultures by a Japanese group.

    Asgard archaea cultivated from marine sediments

    Christa Schleper’s working group at the University of Vienna has now succeeded for the first time in cultivating a representative of this group in higher concentrations. It comes from marine sediments on the coast of Piran, Slovenia, but is also an inhabitant of Vienna, for example in the bank sediments of the Danube. Because of its growth to high cell densities, this representative can be studied particularly well. “It was very tricky and laborious to obtain this extremely sensitive organism in a stable culture in the laboratory,” reports Thiago Rodrigues-Oliveira, postdoc in the Archaea working group at the University of Vienna and one of the first authors of the study.

    Asgard archaea have a complex cell shape with an extensive cytoskeleton

    The remarkable success of the Viennese group to cultivate a highly enriched Asgard representative finally allowed a more detailed examination of the cells by microscopy. The ETH researchers in Martin Pilhofer’s group used a modern cryo-electron microscope to take pictures of shock-frozen cells. “This method enables a three-dimensional insight into the internal cellular structures,” explains Pilhofer. “The cells consist of round cell bodies with thin, sometimes very long cell extensions. These tentacle-like structures sometimes even seem to connect different cell bodies with each other,” says Florian Wollweber, who spent months tracking down the cells under the microscope. The cells also contain an extensive network of actin filaments thought to be unique to eukaryotic cells. This suggests that extensive cytoskeletal structures arose in archaea before the appearance of the first eukaryotes and fuels evolutionary theories around this important and spectacular event in the history of life.

    Future insights through the new model organism

    “Our new organism, called ‘Lokiarchaeum ossiferum’, has great potential to provide further groundbreaking insights into the early evolution of eukaryotes,” comments microbiologist Christa Schleper. “It has taken six long years to obtain a stable and highly enriched culture, but now we can use this experience to perform many biochemical studies and to cultivate other Asgard archaea as well.” In addition, the scientists can now use the new imaging methods developed at ETH to investigate, for example, the close interactions between Asgard archaea and their bacterial partners. Basic cell biological processes such as cell division can also be studied in the future in order to shed light on the evolutionary origin of these mechanisms in eukaryotes.

    This text was published in a similar form by ETH Zurich.

    [ad_2]

    University of Vienna

    Source link

  • Humans continue to evolve with the emergence of new genes

    Humans continue to evolve with the emergence of new genes

    [ad_1]

    Newswise — Modern humans evolutionarily split from our chimpanzee ancestors nearly 7 million years ago, yet we are continuing to evolve. 155 new genes have been identified within the human lineage that spontaneously arose from tiny sections of our DNA. Some of these new genes date back to the ancient origin of mammals, with a few of these “microgenes” predicted to be associated with human-specific diseases. This work is publishing on December 20th in the journal Cell Reports.

    “This project started back in 2017 because I was interested in novel gene evolution and figuring out how these genes originate,” says first author Nikolaos Vakirlis (@vakirlis), a scientist at the Biomedical Sciences Research Center “Alexander Fleming” in Vari, Greece. “It was put on ice for a few years, until another study got published that had some very interesting data, allowing us to get started on this work.”

    Taking the previously published dataset of functionally relevant new genes, the researchers created an ancestral tree comparing humans to other vertebrate species. They tracked the relationship of these genes across evolution and found 155 that popped up from regions of unique DNA. New genes can arise from duplication events that already exist in the genome; however, these genes arose from scratch.

    “It was quite exciting to be working in something so new,” says senior author Aoife McLysaght (@aoifemcl), a scientist at Trinity College Dublin. “When you start getting into these small sizes of DNA, they’re really on the edge of what is interpretable from a genome sequence, and they’re in that zone where it’s hard to know if it is biologically meaningful.”

    Of these 155 new genes, 44 of them are associated with growth defects in cell cultures, demonstrating the importance of these genes in maintaining a healthy, living system. Since these genes are human specific, it makes direct testing difficult. Researchers must seek another way to explore what effects these new genes may have on the body. Vakirlis and his team examined patterns found within the DNA that can hint at if these genes play a role in specific diseases.

    Three of these 155 new genes have disease-associated DNA markers that point to connections with ailments such as muscular dystrophy, retinitis pigmentosa, and Alazami syndrome. Apart from disease, the researchers also found a new gene that is associated with human heart tissue. This gene emerged in human and chimp right after the split from gorilla and shows just how fast a gene can evolve to become essential for the body.

    “It will be very interesting in future studies to understand what these microgenes might do and whether they might be directly involved in any kind of disease,” says Vakirlis.

    “These genes are convenient to ignore because they’re so difficult to study, but I think it’ll be increasingly recognized that they need to be looked at and considered,” says McLysaght. “If we’re right in what we think we have here, there’s a lot more functionally relevant stuff hidden in the human genome.”

    ###

    Financial support provided by the European Research Council and by Greece and the European Union. Aoife McLysaght was a member of the journal’s Advisory Board at the time of this article’s initial submission.

    Cell Reports, Vakirlis et al., “De novo birth of functional microproteins in the human lineage.” https://www.cell.com/cell-reports/fulltext/S2211-1247(22)01696-5 

    Cell Reports (@CellReports), published by Cell Press, is a weekly open access journal that publishes high-quality papers across the entire life sciences spectrum. The journal features reports, articles, and resources that provide new biological insights, are thought-provoking, and/or are examples of cutting-edge research. Visit: http://www.cell.com/cell-reports. To receive Cell Press media alerts, contact [email protected].

    [ad_2]

    Cell Press

    Source link

  • Smilodon’s sabre teeth

    Smilodon’s sabre teeth

    [ad_1]

    Newswise — A team of researchers led by Narimane Chatar, a doctoral student at the EDDyLab of the University of Liège (Belgium), has tested the biting efficiency of Smilodon, an extinct species of carnivore close to the extant felines.  Using high-precision 3D scans and simulation methods, the team has just revealed how these animals managed to bite despite the impressive length of their teeth.

    Ancient carnivorous mammals developed a wide range of skull and tooth shapes throughout their evolution. However, few of these evolutions have yet matched those of the iconic sabre-toothed felid Smilodon. Other groups of mammals, such as the now extinct nimravids, have also evolved a similar morphology, with species having sabre teeth but also much shorter canines, similar to those of the lions, tigers, caracals, domestic cats, etc. that we know today. This phenomenon of similar morphologies appearing in different groups of organisms is known as convergent evolution; felids and nimravids being an amazing example of convergence. As there are no modern equivalents of animals with such sabre-shaped teeth, the hunting method of Smilodon and similar species has remained obscure and hotly debated. It was first suggested that all sabre-toothed species hunted in the same way, regardless of the length of their canines, a hypothesis that is now controversial. So the question remained … how did this variety of ‘sabre-toothed cat’ hunt?

    The enormous canines of the extinct sabre-toothed cat Smilodon imply that this animal had to open its jaw extremely wide, 110° according to some authors, in order to use them effectively,” explains Prof. Valentin Fischer, director of the EDDyLab at ULiège. However, the mechanical feasibility and efficiency of Smilodon and its relatives to bite at such a large angle is unknown, leaving a gap in our understanding of this very fundamental question about sabre-toothed predators.” Using high-precision 3D scanners and analytical methods derived from engineering, an international team of Belgian and North American scientists has just revealed how these animals probably used their impressive weapons.

    Narimane Chatar, a PhD student at the EDDyLab of the University of Liege and lead author of the study, collected a large amount of three-dimensional data. She first scanned and modelled the skulls, mandibles and muscles of numerous extinct and extant species of felids and nimravids. “Each species was analysed in several scenarios: a bite was simulated on each tooth at three different biting angles: 30°, as commonly seen in extant felids, but also larger angles (60° and 90°). In total, we carried out 1,074 bite simulations to cover all the possibilities,” explains Narimane Chatar. To do this, the young researcher used the finite element method. This is an exciting application of the finite element approach, which allows palaeontologists to modify and computationally simulate different bite angles and to subject skull models to virtual stresses without damaging the precious fossil specimens,” says Prof. Jack Tseng, Professor and Curator of Palaeontology at the University of California, Berkeley, and co-author of the study. Our comprehensive analyses provide the most detailed insight to date into the diversity and nuances of sabre tooth bite mechanics.”

    One of the results obtained by the team is the understanding of the distribution of stress (pressure) on the mandible during biting. This stress shows a continuum across the animals analysed, with the highest values measured in species with the shortest upper canines and the lowest stress values measured in the most extreme sabre-toothed species. The researchers also noted that stress decreased with increasing bite angle, but only in sabre-toothed species. However, the way in which these animals transmitted force to the bite point and the deformation of the mandible resulting from the bite were remarkably similar across the dataset, indicating comparable effectiveness regardless of canine length.

    “The results show both the possibilities and the limits of evolution; animals facing similar problems in their respective ecosystems often end up looking alike through convergent evolution. However, Narimane Chatar’s results also show that there can be several ways to be an effective killer, whether you are sabre-toothed or not,” concludes Valentin Fischer. This phenomenon, called ’many-to-one’ systems, means that distinct morphologies can result in a similar function, such as the fact that bears and cats are both efficient fishers. This multiplicity of morphologies indicates that there is no single optimal form of sabre-toothed predator.

    [ad_2]

    University of Liege

    Source link

  • Fossil discovery in storeroom cupboard shifts origin of modern lizard back 35 million years

    Fossil discovery in storeroom cupboard shifts origin of modern lizard back 35 million years

    [ad_1]

    Newswise — A specimen retrieved from a cupboard of the Natural History Museum in London has shown that modern lizards originated in the Late Triassic and not the Middle Jurassic as previously thought.

    This fossilised relative of living lizards such as monitor lizards, gila monsters and slow worms was identified in a stored museum collection from the 1950s, including specimens from a quarry near Tortworth in Gloucestershire, South West England. The technology didn’t exist then to expose its contemporary features.

    As a modern-type lizard, the new fossil impacts all estimates of the origin of lizards and snakes, together called the Squamata, and affects assumptions about their rates of evolution, and even the key trigger for the origin of the group.

    The team, led by Dr David Whiteside of Bristol’s School of Earth Sciences, have named their incredible discovery Cryptovaranoides microlanius meaning ‘small butcher’ in tribute to its jaws that were filled with sharp-edged slicing teeth.

    Dr Whiteside explained: “I first spotted the specimen in a cupboard full of Clevosaurus fossils in the storerooms of the Natural History Museum in London where I am a Scientific Associate. This was a common enough fossil reptile, a close relative of the New Zealand Tuatara that is the only survivor of the group, the Rhynchocephalia, that split from the squamates over 240 million years ago.

    “Our specimen was simply labelled ‘Clevosaurus and one other reptile.’ As we continued to investigate the specimen, we became more and more convinced that it was actually more closely related to modern day lizards than the Tuatara group.

    “We made X-ray scans of the fossils at the University, and this enabled us to reconstruct the fossil in three dimensions, and to see all the tiny bones that were hidden inside the rock.”

    Cryptovaranoides is clearly a squamate as it differs from the Rhynchocephalia in the braincase, in the neck vertebrae, in the shoulder region, in the presence of a median upper tooth in the front of the mouth, the way the teeth are set on a shelf in the jaws (rather than fused to the crest of the jaws) and in the skull architecture such as the lack of a lower temporal bar. There is only one major primitive feature not found in modern squamates, an opening on one side of the end of the upper arm bone, the humerus, where an artery and nerve pass through. Cryptovaranoides does have some other, apparently primitive characters such as a few rows of teeth on the bones of the roof of the mouth, but experts have observed the same in the living European Glass lizard and many snakes such as Boas and Pythons have multiple rows of large teeth in the same area. Despite this, it is advanced like most living lizards in its braincase and the bone connections in the skull suggest that it was flexible.

    “In terms of significance, our fossil shifts the origin and diversification of squamates back from the Middle Jurassic to the Late Triassic,” says co-author Professor Mike Benton. “This was a time of major restructuring of ecosystems on land, with origins of new plant groups, especially modern-type conifers, as well as new kinds of insects, and some of the first of modern groups such as turtles, crocodilians, dinosaurs, and mammals.

    “Adding the oldest modern squamates then completes the picture. It seems these new plants and animals came on the scene as part of a major rebuilding of life on Earth after the end-Permian mass extinction 252 million years ago, and especially the Carnian Pluvial Episode, 232 million years ago when climates fluctuated between wet and dry and caused great perturbation to life.”

    PhD research student Sofia Chambi-Trowell commented: “The name of the new animal, Cryptovaranoides microlanius, reflects the hidden nature of the beast in a drawer but also in its likely lifestyle, living in cracks in the limestone on small islands that existed around Bristol at the time. The species name, meaning ‘small butcher,’ refers to its jaws that were filled with sharp-edged slicing teeth and it would have preyed on arthropods and small vertebrates.”

    Dr Whiteside concluded: “This is a very special fossil and likely to become one of the most important found in the last few decades. It is fortunate to be held in a National Collection, in this case the Natural History Museum, London. We would like to thank the late Pamela L. Robinson who recovered the fossils from the quarry and did a lot of preparation work on the type specimen and associated bones. It was such a pity she did not have access to CT scanning technology to help her observe all the detail of the specimen.”

     

    The paper:

    ‘A Triassic crown clade squamate’ by Whiteside, D. I., Chambi-Trowell, S. A. V., and Benton, M J. Science Advances 8, eabq8274.

     

    [ad_2]

    University of Bristol

    Source link

  • Science ahead of its time: Secret of 157-year old Darwin manuscript

    Science ahead of its time: Secret of 157-year old Darwin manuscript

    [ad_1]

    Newswise — Today is Evolution day – a day commemorating the publication of Charles Darwin’s Origin of Species on 24 November 1859. Darwin’s seminal work is now considered the most influential book of science in history and has inspired countless new disciplines. As recently found by the Darwin Online project at the National University of Singapore (NUS), the book has been translated into fifty languages, far more than any other scientific book.

    Now on the 163rd anniversary of the publication of the Origin of Species, the Darwin Online project releases one of the most exceptional Darwin manuscripts still in private hands. It is also up for auction at Sotheby’s auction house in New York City, making international news, and likely to hit a record price of one million pounds. To understand this unique document, Sotheby’s consulted historian of science Dr John van Wyhe from the NUS Department of Biological Sciences, Fellow of Tembusu College at NUS, and founder and Director of Darwin Online. What was previously taken to be a page of the rough draft of Origin of Species turned out to be much more interesting.

    The document is the result of an autograph hunter named Hermann Kindt who wrote to Darwin in 1865 to request for a written passage from Origin of Species and sign it. This was for Kindt’s magazine, Autographic Mirror, which published examples of the handwriting of famous people. Darwin wrote out a passage from the conclusion to the recent 1861 third 3rd edition of Origin of Species, p. 514:

    “…It is no valid objection [to this theory of evolution] that science as yet throws no light on the far higher problem of the essence or origin of life. Who can explain what is the essence of the attraction of gravity? No one now objects to following out the results consequent on this unknown element of attraction; notwithstanding that Leibnitz formerly accused Newton of introducing ‘occult qualities and miracles into philosophy.’”

    It was published in Kindt’s magazine which is also released today in Darwin Online.

    As a passage from the Origin of Species in Darwin’s own handwriting, and with his rare full signature, this piece is quite unique. But why did Darwin choose this passage in particular from the 490 pages of the book? Dr van Wyhe has found the answer.

    Shortly after the book was published, there were many objections to Darwin’s theory. Some thought that his ‘natural selection’ was not a real force in nature.

    Just then, Darwin happened to read a biography of Isaac Newton in which one of Newton’s critics claimed that his law of gravity was not real but only imaginary “occult qualities and miracles” pushed into science. Darwin was struck by the parallel. His critics thought natural selection was an unreal cause. The day he finished the biography, Darwin wrote to a scientific colleague about it, saying he would use this example to answer critics in future. Almost immediately he had a chance to do so by adding a new passage to the next American printing of Origin of Species, using the quote about Newton. Later the passage appeared in the 3rd and all subsequent editions of the book.

    So now it can be understood why Darwin chose this particular passage to copy out for Kindt in 1865 as he saw it as a powerful defence for his theory of evolution by natural selection. It was as if Darwin was saying, ‘they accused Newton’s law of gravity of being fake and now it is accepted by the whole world. It will be the same for the law of natural selection.’ Darwin was right – his theory of evolution is now the foundation of all the life sciences.

    This unique Darwin manuscript, transcribed with an introduction by Dr van Wyhe, is freely available only at Darwin Online here.

    [ad_2]

    National University of Singapore

    Source link

  • Human evolution wasn’t just the sheet music, but how it was played

    Human evolution wasn’t just the sheet music, but how it was played

    [ad_1]

    Newswise — DURHAM, N.C. — A team of Duke researchers has identified a group of human DNA sequences driving changes in brain development, digestion and immunity that seem to have evolved rapidly after our family line split from that of the chimpanzees, but before we split with the Neanderthals.

    Our brains are bigger, and are guts are shorter than our ape peers.

    “A lot of the traits that we think of as uniquely human, and human-specific, probably appear during that time period,” in the 7.5 million years since the split with the common ancestor we share with the chimpanzee, said Craig Lowe, Ph.D., an assistant professor of molecular genetics and microbiology in the Duke School of Medicine.

    Specifically, the DNA sequences in question, which the researchers have dubbed Human Ancestor Quickly Evolved Regions (HAQERS), pronounced like hackers, regulate genes. They are the switches that tell nearby genes when to turn on and off. The findings appear Nov.23 in the journal CELL.

    The rapid evolution of these regions of the genome seems to have served as a fine-tuning of regulatory control, Lowe said. More switches were added to the human operating system as sequences developed into regulatory regions, and they were more finely tuned to adapt to environmental or developmental cues. By and large, those changes were advantageous to our species.

    “They seem especially specific in causing genes to turn on, we think just in certain cell types at certain times of development, or even genes that turn on when the environment changes in some way,” Lowe said.

    A lot of this genomic innovation was found in brain development and the GI tract. “We see lots of regulatory elements that are turning on in these tissues,” Lowe said. “These are the tissues where humans are refining which genes are expressed and at what level.”

    Today, our brains are larger than other apes, and our guts are shorter. “People have hypothesized that those two are even linked, because they are two really expensive metabolic tissues to have around,” Lowe said. “I think what we’re seeing is that there wasn’t really one mutation that gave you a large brain and one mutation that really struck the gut, it was probably many of these small changes over time.”

    To produce the new findings, Lowe’s lab collaborated with Duke colleagues Tim Reddy, an associate professor of biostatistics and bioinformatics, and Debra Silver, an associate professor of molecular genetics and microbiology to tap their expertise. Reddy’s lab is capable of looking at millions of genetic switches at once and Silver is watching switches in action in developing mouse brains.

    “Our contribution was, if we could bring both of those technologies together, then we could look at hundreds of switches in this sort of complex developing tissue, which you can’t really get from a cell line,” Lowe said.

    “We wanted to identify switches that were totally new in humans,” Lowe said. Computationally, they were able to infer what the human-chimp ancestor’s DNA would have been like, as well as the extinct Neanderthal and Denisovan lineages. The researchers were able to compare the genome sequences of these other post-chimpanzee relatives thanks to databases created from the pioneering work of 2022 Nobel laureate Svante Pääbo.

    “So, we know the Neanderthal sequence, but let’s test that Neanderthal sequence and see if it can really turn on genes or not,” which they did dozens of times.

    “And we showed that, whoa, this really is a switch that turns on and off genes,” Lowe said. “It was really fun to see that new gene regulation came from totally new switches, rather than just sort of rewiring switches that already existed.” 

    Along with the positive traits that HAQERs gave humans, they can also be implicated in some diseases.

    Most of us have remarkably similar HAQER sequences, but there are some variances, “and we were able to show that those variants tend to correlate with certain diseases,” Lowe said, namely hypertension, neuroblastoma, unipolar depression, bipolar depression and schizophrenia. The mechanisms of action aren’t known yet, and more research will have to be done in these areas, Lowe said.

    “Maybe human-specific diseases or human-specific susceptibilities to these diseases are going to be preferentially mapped back to these new genetic switches that only exist in humans,” Lowe said.

    Support for the research came from National Human Genome Research Institute – NIH (R35-HG011332), North Carolina Biotechnology Center (2016-IDG-1013, 2020-IIG-2109), Sigma Xi, The Triangle Center for Evolutionary Medicine and the Duke Whitehead Scholarship.

    CITATION: “Adaptive Sequence Divergence Forged New Neurodevelopmental Enhancers in Humans,” Riley J. Mangan, Fernando C. Alsina, Federica Mosti, Jesus Emiliano Sotelo-Fonseca, Daniel A. Snellings, Eric H. Au, Juliana Carvalho, Laya Sathyan, Graham D. Johnson, Timothy E. Reddy, Debra L. Silver, Craig B. Lowe. CELL, Nov. 23, 2022. DOI: 10.1016/j.cell.2022.10.016

    [ad_2]

    Duke University

    Source link

  • Cultural heritage may influence choice of tools by capuchin monkeys, study suggests

    Cultural heritage may influence choice of tools by capuchin monkeys, study suggests

    [ad_1]

    Newswise — Capuchin monkeys (Sapajus spp.) are among only a few primates that use tools in day-to-day activities. In the Cerrado and Caatinga, they use stones as hammers and anvils to crack open cashew nuts, seed pods of Hymenaea courbaril (West Indian locust; jatobá in Brazil) and other hard foods. 

    In an article published in Scientific Reports, Brazilian researchers show that food hardness and tool size do not always correlate as closely as has been thought. 

    In their study, the researchers observed three populations of bearded capuchin monkeys (Sapajus libidinosus), measuring food hardness, tool size and weight, and local availability of stones. They concluded that culture, defined as information passed on from one generation to the next by social learning, can also influence behavior in this regard. 

    “In one of the populations we analyzed, even when they have stones that are suitable for use on a particular food resource, they may use disproportionately heavy tools, possibly evidencing a cultural trait of that group,” said Tiago Falótico, a researcher at the University of São Paulo’s School of Arts, Sciences and Humanities (EACH-USP) supported by FAPESP.

    The population to which he referred lives in Chapada dos Veadeiros National Park in Goiás, a state in Brazil’s Center-West region. In the study, this population was compared with capuchins living in Serra das Confusões National Park, in Piauí, a state in the Northeast region, and another population that lives in Serra da Capivara National Park, about 100 km away in the same state. 

    The tools are pieces of quartzite and sandstone found in places referred to as processing sites. The animals frequent these sites solely to look for these stones for use as hammers and anvils. One stone is used to pound a nut or seed resting on another stone used as an anvil. 

    “In Serra das Confusões, they use smaller tools to open smaller and softer fruit but use large, heavy hammers to crack coconut shells, which are very hard. In Chapada dos Veadeiros, where there are stones of varying sizes to choose from, they use the heaviest ones even for fragile foods,” Falótico said.

    Not by chance, it was in this latter park that the researchers recorded the heaviest stone lifted by capuchins. An adult male weighs 3.5 kg on average, and they filmed an individual lifting a hammer stone that was later found to weigh 4.65 kg. “They’re champion weightlifters,” he chuckled.

    Measurements

    The findings were the result of a great deal of hard work. The researchers documented the kinds of food most frequently found in the processing sites, such as babassu (Attalea speciosa), West Indian locust, cashew, and wild cassava (Manihot spp). They also documented the stones available, as well as the sizes and weights of the tools they found, measured the hardness of each type of food using a special device, and observed and filmed tool usage in each study area.

    “We expected to find a very close correlation between the type of food and the size and weight of the tool, but the population in Chapada dos Veadeiros mainly used the larger ones even though stones of all sizes are plentiful and they can choose a smaller size. They probably inherited this habit from their ancestors. It’s a cultural difference compared with the other populations,” Falótico said.

    The cultural learning hypothesis is reinforced by the fact that studies in other areas, such as Serra de Itabaiana in Sergipe and Chapada Diamantina in Bahia (both states in the Northeast), involving Sapajus capuchins, stones and the same kinds of fruit and seed have not found processing sites or the use of stone tools for this purpose. In Serra das Confusões, the capuchins use tools to crack open several kinds of food except cashew nuts, which are nevertheless abundant.

    “Their behavior isn’t due to the availability of resources but to cultural heritage,” Falótico said.

    The researchers are now analyzing the genomes of all three populations to see if the cultural differences can be linked to genetic differences.

    The study was also supported by FAPESP via a scholarship awarded to Tatiane Valença, a PhD candidate at EACH-USP.

    Human evolution

    A paper by Falótico and a team of archeologists from Germany, Spain and the United Kingdom, published in the Journal of Human Evolution, reports the results of field experiments conducted to test the potential for accidental flake production during nut cracking by capuchins using various types of rock as anvils.

    Some capuchins ingest or anoint themselves with powder produced by pounding stones. They may also rub the powder on their teeth. Their reasons for doing so are unknown, but the researchers believe one aim may be to combat parasites. In the experiments, flakes were also produced by fragmentation of anvils comprising homogeneous material.

    The monkeys did not use the flakes, which closely resembled the lithic tools found by archeologists at digs around the world. The researchers believe the earliest hominins obtained flakes accidentally before their deliberate production for use as tools.

    “Capuchins may also use flakes as tools in future if an innovative individual starts doing so, and others learn by observing. These primates can therefore serve as a model to help us understand human evolution,” Falótico said.

    A previous study by the same group of researchers showed how lithic tools used by the capuchin population in Serra da Capivara displayed different patterns of wear marks depending on the activities involved (read more at: agencia.fapesp.br/35251). 

    Comparisons of the use-wear marks on tools used by monkeys and hominins could reveal how our earliest ancestors used lithic tools. It may therefore be possible to find out more about human evolution from the study of Brazilian capuchin monkeys.

    The article “Stone tools differences across three capuchin monkey populations: food’s physical properties, ecology, and culture” is at: www.nature.com/articles/s41598-022-18661-3. 

    About São Paulo Research Foundation (FAPESP)

    The São Paulo Research Foundation (FAPESP) is a public institution with the mission of supporting scientific research in all fields of knowledge by awarding scholarships, fellowships and grants to investigators linked with higher education and research institutions in the State of São Paulo, Brazil. FAPESP is aware that the very best research can only be done by working with the best researchers internationally. Therefore, it has established partnerships with funding agencies, higher education, private companies, and research organizations in other countries known for the quality of their research and has been encouraging scientists funded by its grants to further develop their international collaboration. You can learn more about FAPESP at www.fapesp.br/en and visit FAPESP news agency at www.agencia.fapesp.br/en to keep updated with the latest scientific breakthroughs FAPESP helps achieve through its many programs, awards and research centers. You may also subscribe to FAPESP news agency at http://agencia.fapesp.br/subscribe

    [ad_2]

    Fundacao de Amparo a Pesquisa do Estado de Sao Paulo

    Source link

  • What Darwin would discover today

    What Darwin would discover today

    [ad_1]

    Newswise — “If Charles Darwin had had the opportunity to dive off the Cape Verde Islands, he would have been completely thrilled”, Eduardo Sampaio is convinced, because Darwin would have seen a fascinating, species-rich landscape. But he lacked the diving equipment. Thus, in his notes The Voyage of the Beagle, Darwin described Cape Verde as a barren landscape.

    Eduardo Sampaio, affiliate member of the Cluster of Excellence “Centre for the Advanced Study of Collective Behaviour” (CASCB) at the University of Konstanz, had quite the opposite experience. He was invited on board the ship Captain Darwin by filmmaker Victor Rault to continue his octopus research.

    Victor Rault, 30, set sail from Plymouth on the Captain Darwin in 2021, following in the footsteps of Darwin’s HMS Beagle. He wants to explore how the ecosystem has changed since Darwin’s voyage on the HMS Beagle in 1832. Researchers and citizens have been invited to travel along and conduct experiments in the spirit of Darwin. “When Victor told me about his project, I was baffled”, recalls biologist Eduardo Sampaio from Portugal. He says: “It was immediately clear to me that it’s an excellent idea to retrace the path of Charles Darwin. I was more than keen to jump on board!”

    What do octopuses see in a mirror image?
    Eduardo Sampaio spent ten days on the Captain Darwin. The focus was on the dives: The biologist, who works with the Max Planck Institute of Animal Behavior, actually wanted to observe the joint hunting behaviour of octopuses and fish. However, as it was mating season, the animals rarely showed themselves. If they came out, they wanted to interact with other octopuses and did not hunt at all.

    So, he spontaneously changed his research project and conducted a mirror test instead: “We wanted to determine whether the octopuses could realize that they were seeing another individual in the mirror.” In the evening on board, the crew watched the video footage: “When the octopus approached the mirror, it changed colour – but only the side facing the mirror changed. That was very fascinating to watch”, says Eduardo Sampaio. In a further experiment, the researcher now wants to test whether the octopuses can even recognize themselves.

    Bringing Darwin’s research style up to date
    In the evenings, Eduardo Sampaio read Darwin’s The Origin of Species, because “it inspired me”. Often, he wondered: “How can we update Darwin’s kind of scientific work with the new methods we have today, like machine learning and computer vision, to better understand how animals move in their natural habitats or use different strategies to exploit social information?” He does not have an answer yet, but may find it the next time he sails on the Captain Darwin.

    Great support for scientists who do not have the necessary resources
    Eduardo Sampaio will be back on board the Captain Darwin: “This trip, launched as a Citizen Science project, is a great support for researchers who don’t have the means to do this kind of field research, especially for researchers from disadvantaged areas and in countries where research structures are not so well equipped.” Much of the work that researchers usually have to handle themselves was taken over, such as obtaining permits, purchasing equipment and raising funds. “I also realized that citizens can play a much more active role in science than just collecting data”, says Eduardo Sampaio, who hopes that this sailing trip will be a prelude to more exciting Citizen Science expeditions. Eduardo Sampaio and Victor Rault also wrote a report about the collaboration published in PLOS Biology on 15 November 2022.

    Key facts

    • Dr Eduardo Sampaio from the Cluster of Excellence “Centre for the Advanced Study of Collective Behaviour” and researcher at the Max Planck Institute of Animal Behavior participated in a Citizen Science-led expedition
    • Publication on the benefits of such research projects in PLOS Biology: Sampaio E, Rault V (2022) Citizen-led expeditions can generate scientific knowledge and prospects for researchers. PLoS Biol 20(11):e3001872. https://doi.org/10.1371/journal.pbio.3001872

    [ad_2]

    University of Konstanz

    Source link

  • Gene plays important role in embryonic development

    Gene plays important role in embryonic development

    [ad_1]

    Newswise — An international study led by the medical Faculty of the University of Bonn has identified a gene that plays an important role in the development of the human embryo. If it is altered, malformations of various organ systems can result. The gene emerged very early in evolution. It also exists in zebrafish, for example, and performs a similar function there. The results have now been published in the Journal of Medical Genetics.

    The researchers tracked down the gene when they studied two individuals with congenital malformations. “It was a man and his niece,” explains Dr. Gabriel Dworschak. “Both had malformed kidneys, urinary tract and esophagus, and the man also had a malformed right arm and heart.”

    The physician at the University Children’s Hospital in Bonn conducts research on rare genetic diseases at the Institutes of Anatomy and Human Genetics. When the team looked at the genetic makeup of the family members, they came across an anomaly: A gene called SHROOM4 was altered in affected individuals compared to healthy individuals.

    SHROOM4 was already familiar from another context: It was known to play a key role in brain function. Mutations can result in intellectual impairment, epileptic seizures and behavioral abnormalities. “Our findings indicated though, that it may play a broader role in embryonic organ development,” Dworschak explains.

    The team from Bonn searched internationally for other cases in which abnormalities in the SHROOM4 gene had also been found – and succeeded: “Together with our cooperation partners, this led us to four more affected individuals from three families,” says Prof. Dr. Heiko Reutter, who has since moved from the University Hospital Bonn to the University of Erlangen-Nuremberg. “All of them had the SHROOM4 gene altered, but not always in the same way.”

    Zebrafish also needs SHROOM4

    However, this did not necessarily clarify whether SHROOM4 variants were actually responsible for the malformations. But there is an animal that has a very similar gene: the zebrafish. It serves as a model organism in many genetic studies today – and not only because it is easy to keep in a species-appropriate manner and to reproduce quickly: The skin of its larvae is almost transparent. This makes it easy to observe the animals’ embryonic development under the light microscope. “Here at the University Hospital, we have the advantage that the research group led by Prof. Dr. Benjamin Odermatt from the Institute of Neuroanatomy works a lot with zebrafish,” stresses Dr. Caroline Kolvenbach, who was also involved in the study of SHROOM4. “This expertise came in handy in our study.”

    The researchers almost completely inactivated SHROOM4 in the larvae. The animals then showed malformations similar to those seen in the patients. If, on the other hand, larvae with SHROOM4 switched off were injected with the intact human genetic material, they developed almost normally. “This shows first that they absolutely need a functional SHROOM4 for healthy development; and second, that the human gene can still take over the function of the fish gene,” Dworschak emphasizes.

    The team now wants to find out which part the gene plays in embryonic development. “We assume that it is needed for very basic processes in the cell,” says Dworschak. “It’s hard to explain otherwise why changes in the same gene cause such a variety of symptoms.”

    Small piece in the mosaic of an extremely complex picture

    How a mouse, a dog or a human being develops from a fertilized ovum is still not fully understood. This is because the ovum has the ability to form any type of tissue in the organism, whether it is bone, skin, muscle or the brain. Its daughter cells are genetically identical to it; so in principle they should be able to do the same. But at a very early stage, certain programs are activated in their cells that irrevocably determine their developmental fate.

    This process must be coordinated down to the finest detail. Because only then it is ensured that the eyes form in the appropriate spot on the face, while other cells very close by differentiate into the nasal cartilage. Surprisingly, however, there is no conductor wielding the baton. It is as if a Lego spaceship were assembling itself – only infinitely more complicated. “Our study is a small piece of the mosaic to this picture, which is still largely incomplete,” Dworschak says.

    Participating institutions and funding:

    In addition to the University of Bonn and the University Hospital Bonn, the study involved Children’s Mercy Hospital (USA), the Medical University of Silesia (Poland), the University of Zielona Góra (Poland), the University of Southern Denmark (Denmark), the University of Cologne, the University of Heidelberg, the University of Erlangen-Nuremberg, Medeor Hospital Lodz (Poland), and Goethe University Frankfurt. The work was supported by the German Research Foundation (DFG), the BONFOR program of the University Hospital Bonn, the Else Kröner-Fresenius Foundation, the Luise and Horst Köhler Foundation, and the National Institutes of Health (USA).

    Publication: Caroline M. Kolvenbach et al.: X-linked variations in SHROOM4 are implicated in congenital anomalies of the urinary tract, the anorectal, the cardiovascular, and the central nervous system; Journal of Medical Genetics; DOI: 10.1136/jmg-2022-108738

    [ad_2]

    University of Bonn

    Source link

  • New pterosaur species found in sub-Saharan Africa

    New pterosaur species found in sub-Saharan Africa

    [ad_1]

    Newswise — DALLAS (SMU) – With wings spanning nearly 16 feet, a new species of pterosaurs has been identified from the Atlantic coast of Angola. 

    An international team, including two vertebrate paleontologists from SMU, named the new genus and species Epapatelo otyikokolo. This flying reptile of the dinosaur age was found in the same region of Angola as fossils from large marine animals currently on display at the Smithsonian’s National Museum of Natural History. 

    Pterosaur fossils that date back to the Late Cretaceous are extremely rare in sub-Saharan Africa, said team member Michael J. Polcyn, research associate in the Huffington Department of Earth Sciences and senior research fellow, ISEM at SMU (Southern Methodist University). 

    “This new discovery gives us a much better understanding of the ecological role of the creatures that were flying above the waves of Bentiaba, on the west coast of Africa, approximately 71.5 million years ago,” Polcyn said.

    Renowned paleontologist Louis L. Jacobs, SMU professor emeritus of earth sciences and president of ISEM, an interdisciplinary institute at the university, also collaborated on the research. The team’s findings were published in the journal Diversity. 

    Epapatelo otyikokolo is believed to have been a fish-eating pterosaur that behaved similarly to large modern-day seabirds.

    “They likely spent time flying above open-water environments and diving to feed, like gannets and brown pelicans do today,” Jacobs said. “Epapatelo otyikokolo was not a small animal, and its wingspan was approximately 4.8 m, or nearly 16 feet.” 

    But fossils discovered since the study suggest that some of the newly identified pterosaur species could have been even larger creatures, Polcyn said. Pterosaurs were impressive creatures, with some of the largest species having wingspans of nearly 35 feet.

    The genus name ‘Epapatelo’ is the translation of the word from the Angolan Nhaneca dialect meaning “wing”, and the species name “otyikokolo” is the translation of ‘lizard.’ The Nhaneca or Nyaneka people are an Indigenous group from Angola’s Namibe Province, the region where the fossils were found.

    The lead author of the study was Alexandra E. Fernandes, of Museu da Lourinhã, Universidade NOVA de Lisboa and The Bavarian State Collection for Paleontology and Geology. Other co-authors include Octávio Mateus of Universidade NOVA de Lisboa and Museu da Lourinhã; Brian Andres of the University of Sheffield; Anne S. Schulp of the Naturalis Biodiversity Center and Utrecht University in the Netherlands; and Antonio Olímpio Gonçalves of the Universidade Agostinho Neto in Angola.

    Jacobs and Polcyn forged the Projecto PaleoAngola partnership with collaborators in Angola, Portugal, and the Netherlands to explore and excavate Angola’s rich fossil history, and began laying the groundwork for returning the fossils to the West African nation. Back in Dallas, Jacobs, Polcyn, and research associate Diana Vineyard went to work over a period of 13 years with a small army of SMU students to prepare the fossils excavated by Projecto PaleoAngola.

    This international team discovered and collected the fourteen bones from Epapatelo otyikokolo in Bentiaba, Angola, starting in 2005. Bentiaba is located on a section of Angola coastline that Jacobs has called a “museum in the ground” because so many fossils have been found in the rocks there. 

    Many of those fossils are currently on display at the Smithsonian’s National Museum of Natural History “Sea Monsters Unearthed” exhibit, which was co-produced with SMU. It features large marine reptiles from the Cretaceous Period — mosasaurs, turtles, and plesiosaurs.

    About SMU

    SMU is the nationally ranked global research university in the dynamic city of Dallas. SMU’s alumni, faculty and nearly 12,000 students in eight degree-granting schools demonstrate an entrepreneurial spirit as they lead change in their professions, communities and the world.

    [ad_2]

    Southern Methodist University

    Source link

  • Linking mass extinctions to the expansion and radiation of land plants

    Linking mass extinctions to the expansion and radiation of land plants

    [ad_1]

    Newswise — Boulder, Colo., USA: The Devonian Period, 419 to 358 million years ago, was one of the most turbulent times in Earth’s past and was marked by at least six significant marine extinctions, including one of the five largest mass extinctions ever to have occurred. Additionally, it was during the Devonian that trees and complex land plants similar to those we know today first evolved and spread across the landscape. This evolutionary advancement included the development of significant and complex root systems capable of affecting soil biogeochemistry on a scale the ancient Earth had yet to experience.

    It has been theorized that these two seemingly separate events, marine extinctions and plant evolution and expansion, were intricately linked in the Devonian. Specifically, it has been proposed that plant evolution and root development occurred so rapidly and on such a massive scale that nutrient export from the land to the ancient oceans would have drastically increased. This scenario is seen in modern systems where anthropogenically sourced nutrient export has vastly increased the nutrient load into areas such as the Gulf of Mexico and the Great Lakes, leading to large-scale algal blooms that ultimately deplete the oxygen in the water column. This effect, known as eutrophication, magnified on a global scale, would have been catastrophic to ancient oceans, fueling algal blooms that would have depleted most of the ocean’s oxygen.

    The key to linking mass extinctions and the expansion and radiation of land plants lies in identifying a nutrient flux elevated above background levels, linking that nutrient flux to either indirect or direct evidence of the presence of deeply rooting land plants and finally showing that this phenomenon occurred in multiple locations and times.

    This study, the first of its kind, was able to do precisely that by utilizing geochemical records from ancient lake deposits in Greenland, northern Scotland, and Orkney. Utilizing lake records, elevated values of the nutrient phosphorus were detected in five distinct locations during the height of plant evolution and expansion in the Devonian. In each case, elevated values of nutrient input were coincident with evidence of the presence of early trees in the form of fossilized spores and, in some cases, fossilized stems of the earliest deeply rooting tree, Archaeopteris. In two cases, that evidence coincided with a Devonian marine extinction event, including the most significant Devonian mass extinction, the Frasnian–Famennian extinction (also known as the Late Devonian mass extinction).

    Additionally, this study, published yesterday in the Geological Society of America Bulletin, linked the periodic wet/dry climate cycles known to exist in the region during the Devonian with specific episodes of plant colonization. While elevated nutrient export was noted during both wet and dry climate cycles, the most significant export events occurred during wet cycles, suggesting that plant expansion was episodic and tied to climate cyclicity.

    The episodic nature of plant expansion could help explain why there are at least six significant marine extinctions in the Devonian. While the scope of this study was limited to a single geographic region, it is likely that these events occurred throughout the Devonian Earth. The colonization of different types of land plants in different regions and at different times would have resulted in episodic nutrient pulses significant enough to sustain eutrophication and cause (or at least contribute) to the numerous marine extinction events throughout the mid- to Late Devonian.

    FEATURED ARTICLE
    Enhanced terrestrial nutrient release during the Devonian emergence and expansion of forests: Evidence from lacustrine phosphorus and geochemical records
    Matthew Smart; Gabriel Filippelli; William Gilhooly; John Marshall; Jessica Whiteside
    Contact: Matthew Smart, [email protected], Indiana University–Purdue University Indianapolis, Earth Sciences, Indianapolis, Indiana
    URL: https://pubs.geoscienceworld.org/gsa/gsabulletin/article-abstract/doi/10.1130/B36384.1/618814/Enhanced-terrestrial-nutrient-release-during-the

    GSA BULLETIN articles published ahead of print are online at https://bulletin.geoscienceworld.org/content/early/recent . Representatives of the media may obtain complimentary copies of articles by contacting Kea Giles. Please discuss articles of interest with the authors before publishing stories on their work, and please make reference to The Geological Society of America Bulletin in articles published. Non-media requests for articles may be directed to GSA Sales and Service, [email protected]

    # # #

    [ad_2]

    Geological Society of America (GSA)

    Source link

  • New study finds our ancient relatives were not so simple after all

    New study finds our ancient relatives were not so simple after all

    [ad_1]

    Newswise — Researchers at the University of Nottingham have solved an important piece of the animal evolution puzzle, after a new study revealed that our ancient ancestors were more complex than originally thought. 

    Way back in our distant evolutionary history, animals underwent a major innovation. They evolved to have a left and right side, and two gut openings. This brought about a plethora of significant advantages in terms of propelling themselves directly forward at increased speed through the early seas, from finding food and extracting nutrients to avoiding being eaten themselves. It was such a successful strategy that, today, we share our planet with a huge diversity of other animals with bilateral symmetry and two gut openings just like us humans. They include animals as diverse as starfish, sea cucumbers, elephants, crickets, and snails. They also include an enigmatic group of very simple marine worms called Xenacoelomorphs, who lack many of the complex features of their fancier looking cousins. 

    For years, scientists have debated who is more closely related to who in this diverse collection of bilaterally symmetrical animals. Some experts argue that Xenacoelomorphs mark the first group to branch in that major jump in innovation from animals with circular body plans (e.g. jelly fish and corals) to bilateral symmetry. If this was the case, then the first bilaterian itself was also a very simple animal. Others argued for different placements of Xenacoelomorphs on the family tree.  

    However, a research team, led by Dr Mary O’Connell at the University of Nottingham has found that Xenacoelomorphs branch much later in time. They are not the earliest branch on the bilaterian family tree and their closest relatives are far more complex animals, like star fish. This means that Xenacoelomorphs have lost many of the complex features of their closest relatives, challenging the idea that evolution leads to ever more complex and intricate forms. Instead, the new study shows that loss of features is an important factor in driving evolution.  

    Dr Mary O’Connell, Associate Professor in Life Sciences at the University of Nottingham says: “There are many fundamental questions about the evolution of animals that need to be answered. Many parts of this family tree that are not known or not resolved. But what an exciting time to be an evolutionary biologist with the availability of exquisite genome data from the beautiful diversity of species we currently have on our planet, allowing us to unlock secrets of our most distant past.”  

    The paper, titled ‘Filtering artifactual signal increases support for Xenacoelomorpha and Ambulacraria sister relationship in the animal tree of life’ has been published in the peer-reviewed journal, Current Biology. It details the application of a special phylogenetic technique to help in extracting signal from noise over deep time, showing increased support for Xenacoelomorphs being sister to ambulacraria (e.g. star fish) rather than being the deepest diverging of the bilateria.  

    The research team at the University of Nottingham will now explore other challenging family trees and other connections between genome changes and phenotypic diversity.  

    [ad_2]

    University of Nottingham

    Source link

  • Footprints indicate the presence of man in Southern Spain in the Middle Pleistocene, 200,000 years earlier than previously thought

    Footprints indicate the presence of man in Southern Spain in the Middle Pleistocene, 200,000 years earlier than previously thought

    [ad_1]

    Newswise — The researcher and GRS Radioisotopes technician from the University of Seville, Jorge Rivera, has participated in an incredible discovery that is unique in Europe. After applying optically-stimulated luminescence technique at the Centre for Research, Technology and Innovation laboratories at the University of Seville (CITIUS) and at CENIEH, to hominin footprints found at Matalascañas in 2020, it was possible to determine that they are in fact 200,000 years older than previously suspected. This would mean that pre-Neanderthals would have lived in the Doñana area during the Middle Pleistocene, around 295,800 years ago.

    The research, led by the Professor of Paleontology at the University of Huelva, Eduardo Mayoral, was published by Scientific Reports, one of the publications of the Nature group, on 19 October.

    The technique

    Optically-stimulated luminescence is a method used to find the absolute age of sediments that have been fully exposed to sunlight.

    Scientific milestone

    The discovery in June 2020 of hominin footprints more than 106,000 years old next to El Asperillo (Matalascañas, Huelva) was a revolution for the scientific world, so much so that it was considered one of the most important discoveries of that year. But now, the publication of this new paper has confirmed what some experts suspected at the time: those footprints were much older and are in fact 200,000 years older than previously thought. While it was previously placed in the Upper Pleistocene, the evidence now points clearly to the Middle Pleistocene, and to its being 295,800 years old, making it a unique record in Europe, since there is no better site in the world in terms of number, age and area than that of the El Asperillo beach for hominin fossil footprints.

    After collecting samples from the various levels, and another two later to compare the first results, the age of the fossil remains was established and points to the Middle Pleistocene, a crucial moment between different climatic stages, between a warm period, MIS 9 (360,000-300,000 years ago), in transition to MIS 8 (300,000-240,000 years ago), in which a major glaciation took place.

    The age is thus specified at 295,800 years, with a margin of error of 17,800 years, according to the data collected from the four samples of sedimentary levels in the cliffs of El Asperillo where the site was found, initially 87 footprints, which now has a record of more than 300 footprints, of which 10% are considered well-preserved. With the exception of those from Matalascañas, it is noted that no other hominin footprints are known between the climatic stages MIS9 and MIS 8 of the Middle Pleistocene. That is why it is questioned whether they belong to Neanderthals.

    But are they Neanderthals?

    At first they were thought to be Neanderthals, but that is now in doubt. The main hypothesis among the scientists is that they are individuals of the Neanderthal lineage, among which Homo heidelbergensis and Homo neanderthalensis have been associated. The hypothesis that they are pre-neanderthal hominins is feasible. Precisely for this reason, the Matalascañas footprints are now more valuable due to their contribution to the fossil records of hominins in the Middle Pleistocene, which is very poor in Europe because of the scarcity of deposits with footprints. Until now, according to the Nature paper, footprints this period have only been found at Terra Amata and Roccamonfina (Italy), which were dated to between 380,000 and 345,000 years ago, with records of Homo heidelbergensis. They are the only ones older than that at Huelva in this era. After these, Biache-Vaast (France) and Theopetra (Greece) sites, from 236,000 to 130,000 years ago, are attributed to Homo neanderthalensis. In this context, the length range of all the footprints found at Matalascañas, from 14 to 29 centimetres, is similar to that found at European sites, such as Theopetra (14-15 centimetres), Roccamonfina (24-27 cm) and Terra Amata (24 cm).

    In any case, the experts highlight the singularity of the Matalascañas discovery, whose new dating has questioned the existing paradigms and has required a deep analysis before accepting its conclusions. 

    The new chronology now establishes a change in the scenario that then prevailed on the coast of the Gulf of Cádiz, with human settlements in a more temperate and humid climate than in the rest of Europe, with high water tables and abundant vegetation.

    In that same period the sea level would have been about 60 metres below its current level. This implies that the coast would be more than 20 kilometres from where it is today, which is how there would have been a great coastal plain, with large flood-prone areas, in which the footprints discovered in mid-2020 would have been made.

    The site’s new dating also affects the vertebrate animals found, since the hominin traces there also included footprints of large mammals such as straight-tusked elephants, gigantic bulls (aurochs) and boars. It was the fauna that inhabited Doñana 300,000 years ago and not 100,000 years ago, as other investigations stated.

    International team

    The paper, New dating of the Matalascañas footprints provides new evidence of the Middle Pleistocene (MIS 9-8) hominin paleoecology in southern Europe, is the result of the work of an international team of scientists led by the Professor of Paleontology at the University of Huelva, Eduardo Mayoral, alongside the lecturer Antonio Rodríguez and Professor of Stratigraphy Juan Antonio Morales, all of the Department of Earth Sciences of the Faculty of Experimental Sciences, who are also members of the Centre for Scientific and Technological Research (CCTH) at UHU, as well as Jérémy Duvau, a researcher at the Museum National d’Histoire Naturelle (France); Ana Santos, from the University of Oviedo; Ricardo Díez-Delgado, from the Doñana-CSIC Biological Station; Jorge Rivera, from the University of Seville; Asier Gómez-Olivencia, from the University of the Basque Country; and Ignacio Díaz, from the University of Río Negro (Argentina).

    [ad_2]

    University of Seville

    Source link

  • Old bone links lost American parrot to ancient Indigenous bird trade

    Old bone links lost American parrot to ancient Indigenous bird trade

    [ad_1]

    Newswise — For centuries, Indigenous communities in the American Southwest imported colorful parrots from Mexico. But according to a study led by The University of Texas at Austin, some parrots may have been captured locally and not brought from afar.  

    The research challenges the assumption that all parrot remains found in American Southwest archaeological sites have their origins in Mexico. It also presents an important reminder: The ecology of the past can be very different from what we see today.     

    “When we deal with natural history, we can constrain ourselves by relying on the present too much,” said the study’s author, John Moretti, a doctoral candidate at the UT Jackson School of Geosciences. “These bones can give us kind of a baseline view of the animal life of the ecosystems that surrounded us before huge fundamental changes that continue today began.”  

    The study was published in print in the September issue of The Wilson Journal of Ornithology.  

    Parrots are not an uncommon find in southwestern archaeological sites dating as far back as the 7th or 8th centuries. Their remains have been found in elaborate graves and buried in trash heaps. But no matter the condition, when archaeologists have discovered parrot bones, they usually assumed the animals were imports, said Moretti.  

    There’s good reason for that. Scarlet macaws — the parrot most commonly found in the archaeological sites — live in rainforest and savannahs, which are not part of the local landscape. And researchers have discovered the remains of ancient parrot breeding facilities in Mexico that point to a thriving parrot trade.   

    But there is more to parrots than macaws. In 2018, Moretti found a lone ankle bone belonging to a species known as the thick-billed parrot. It was part of an unsorted bone collection recovered during an archaeological dig in the 1950s in New Mexico.   

    “There was a lot of deer and rabbit, and then this kind of anomalous parrot bone,” said Moretti, a student in the Jackson School’s Department of Geological Sciences. “Once I realized that nobody had already described this, I really thought there was a story there.” 

    Thick-billed parrots are an endangered species and do not live in the United States today due to habitat loss and hunting. But that was not the case even a relatively short time ago. As recently as the 1930s, their range stretched from Arizona and New Mexico to northern Mexico, where they live today. The boisterous, lime-green birds are also very particular about their habitat. They dwell only in mountainous old-growth pine forests, where they nest in tree hollows and dine almost exclusively on pine cones.  

    With that in mind, Moretti decided to investigate the connection between pine forests in New Mexico and Arizona and the remains of thick-billed parrots found at archaeological sites. He found that of the 10 total archaeological sites with positively identified thick-billed parrot remains, all contained buildings made of pine timber, with one settlement requiring an estimated 50,000 trees. And for half the sites, suitable pine forests were within 7 miles of the settlement.  

    Moretti said that with people entering parrot habitat, it’s plausible to think they captured parrots when gathering timber and brought them home.  

    “This paper makes the hypothesis that these [parrots] were not trade items,” Moretti said. “They were animals living in this region that were caught and captured and brought home just like squirrels and other animals that lived in these mountains.”  

    Moretti relied on thick-billed parrot bones from the United States and Mexico permanently archived in collections at The University of Kansas Biodiversity Institute and the Smithsonian Institution to conclusively identify the lone bone that sparked the research. Mark Robbins, an evolutionary biologist and the collection manager of the ornithological collections at The University of Kansas, said this study shows the value of natural history collections and the innumerable ways they assist with research.  

    “The scientists who originally collected those specimens, they had no idea they would be used in this fashion,” Robbins said. “You can revisit old questions or formulate new questions based on these specimens.”  

    The research was funded by the Museum of Texas Tech University, where Moretti earned a master’s degree.   

    [ad_2]

    University of Texas at Austin (UT Austin)

    Source link

  • It’s Not the Heat, It’s the Humidity: Water Loss Hurts Bees Most in the Desert

    It’s Not the Heat, It’s the Humidity: Water Loss Hurts Bees Most in the Desert

    [ad_1]

    Newswise — (San Diego) October 29, 2022—Digger bees lose large amounts of water during flight, which compromises their activity period and survival in the desert heat. Researchers from Arizona State University will present their work this week at the American Physiological Society (APS) Intersociety Meeting in Comparative Physiology: From Organism to Omics in an Uncertain World conference in San Diego. 

    “Water loss appears to be a critical problem for male digger bees. Climate change will very likely challenge their important ecological functions.” —Meredith Johnson

    Climate change plays a role in the physiological evolution and survival of animals of all sizes. Desert animals, already acclimated to high temperatures, use evaporative heat loss to help prevent overheating. However, the sometimes-limited ability to replenish water loss means the danger of dehydration is a challenge for desert animals, including the Sonoran Desert digger bee.

    Bees are an integral part of the ecosystem due to their ability to pollinate—more than 80% of flowering plants rely on insect pollinators. When bees become unable to pollinate sufficiently—due to lack of food or other changes in their environment—plant biodiversity decreases and plant-eating animals are affected. A large percentage of food crops, including fruits, nuts and vegetables, also depend on pollination. Researchers explored the effects of heat, water stress and food availability on male digger bees in the Arizona Uplands, a region of the Sonoran Desert.

    During the study, air temperatures increased from around 66 degrees F in the early morning—when the bees began to fly to a mating site—to about 100 degrees at midday, when they typically stop flying for the day. In addition, no plants were in bloom at the study site to provide nectar for the bees to drink at the time of the study. Marking techniques used by the research team suggest that the bees survive for about a week, which means they are finding nectar somewhere in the desert. Researchers think the bees may be traveling for some distance during the later—and hotter—part of the day to find food.

    The researchers also examined the bees’ body temperature and body water content throughout the day. The hottest body temperature measurement was approximately 111 degrees F. Digger bees can withstand body temperatures around 125 degrees during flight, suggesting that overheating is not why the bees stopped flying before midday, explained Meredith Johnson, a doctoral candidate at Arizona State University and first author of the study.

    Water loss is a bigger problem for the insects. “These bees lose 17% of their body water content per hour, with the amount slightly increasing as the air temperature [rises],” Johnson said. “Loss of about 50% of total body water content is lethal, suggesting that these bees can maximally fly for about three hours.”

    The flying time constraint is important to note, as typically bees need to fly for six or seven hours each day searching for mating opportunities. Without sufficient time to mate, the bee population will shrink in the future.

    “Water loss appears to be a most critical problem for male digger bees. Climate change will very likely challenge their important ecological functions,” Johnson said.

    Physiology is a broad area of scientific inquiry that focuses on how molecules, cells, tissues and organs function in health and disease. The American Physiological Society connects a global, multidisciplinary community of more than 10,000 biomedical scientists and educators as part of its mission to advance scientific discovery, understand life and improve health. The Society drives collaboration and spotlights scientific discoveries through its 16 scholarly journals and programming that support researchers and educators in their work. 

     

    [ad_2]

    American Physiological Society (APS)

    Source link

  • Math Model Shows Climate Change Puts Rainforest Animal’s Survival in Jeopardy

    Math Model Shows Climate Change Puts Rainforest Animal’s Survival in Jeopardy

    [ad_1]

    Newswise — (San Diego) October 29, 2022—A South American marsupial with ties to an ancient line of animals may go extinct in the next half-century due to warming temperatures. Researchers from the Universidad Austral de Chile will present a mathematical model of the monito del monte’s survival predictions this week at the American Physiological Society (APS) Intersociety Meeting in Comparative Physiology: From Organism to Omics in an Uncertain World conference in San Diego. 

    The monito del monte, native to the rainforests of South America, is a marsupial in the relict family Microbiotheriidae. These tiny animals typically weigh about 20 grams (0.7 ounce) and measure around 3 to 5 inches long. Monitos reproduce and prepare for winter hibernation during the summer. Preparation includes eating as much as possible—including fruit, insects, small birds and other dead animals—to store as body fat. Researchers estimate that monitos need to have fat reserves that are almost twice their body weight to survive the winter.

    Climate change predictions show that ambient temperatures in coastal Chile will increase an estimated 36.5 degrees F over the next 50 years. This will have a large impact on the ability of the monito population to survive the winter. The warmer temperatures will cause the animals to come out of hibernation earlier than usual, and they will be unable to find food during the winter, explained Roberto Nespolo Rossi, PhD, first author of the study. Nespolo and his research team developed a mathematical model to estimate survival rates for the monito population in the advent of global warming.

    The mathematical model uses an algebraic formula to connect days of winter survival with the ambient temperature. The calculations are based on the assumption that all of the monitos’ daily energy expenditure during hibernation comes from the fat stores they have accumulated during the warmer months.

     

    Energy content of fat (kilojoule per gram) X Fat stores (grams)

    ­­­­­_______________________________________________________ 

    Daily energy expenditure (kilojoule per day)

    The model “is one of the few predictive models built on physiological parameters, so it can be applied to other hibernators, for which there is plenty of physiological data,” Nespolo said. “Our predictions for 50 years … indicate that most coastal populations [of monitos] will go extinct,” he added. This is especially important because the monito, sometimes referred to as a “living fossil,” is the last living relative of the ancient marsupial order Microbiotheria.

    Physiology is a broad area of scientific inquiry that focuses on how molecules, cells, tissues and organs function in health and disease. The American Physiological Society connects a global, multidisciplinary community of more than 10,000 biomedical scientists and educators as part of its mission to advance scientific discovery, understand life and improve health. The Society drives collaboration and spotlights scientific discoveries through its 16 scholarly journals and programming that support researchers and educators in their work. 

    [ad_2]

    American Physiological Society (APS)

    Source link

  • Discovering the unknown processes of the evolutionary history of green lizards in the Mediterranean

    Discovering the unknown processes of the evolutionary history of green lizards in the Mediterranean

    [ad_1]

    Newswise — The evolutionary clade and biodiversity of green lizards of the genera Lacerta and Timon —reptiles common in the Mediterranean basin and surrounding areas of the European continent, North Africa and Asia— have never been studied in detail from the perspective of historical biogeography. Now, a paper published in the Journal of Biogeography presents a new scenario for deciphering the potential evolutionary processes that have acted —separately or together— to give rise to the biodiversity of species in this group in Mediterranean ecosystems.

    The study is led by the researcher Antigoni Kaliontzopoulou, from the Faculty of Biology and the Biodiversity Research Institute (IRBio) of the University of Barcelona. Teams from the National Museum of Natural Sciences (MNCN-CSIC), the University of Vigo and the University of Porto (Portugal), among other institutions, are also participating.

    The hidden history of the evolution of green lizards

    Today, green lizard populations are threatened by numerous factors: the destruction and fragmentation of their natural habitat; the disappearance of traditional agricultural practices; the use of pesticides; the increase in cat populations in humanised areas; climate change, and, in addition, the fatal accidents they suffer in roads. However, although there are indications that some populations are in population decline, the International Union for Conservation of Nature (IUCN) has not yet listed these reptiles as endangered species.

    According to previous studies, the evolution of the green lizard group was the result of a combination of evolution and the conservatism of ecological niches, “but the relative role of geological history and niche dynamics had not yet been tested”, says Antigoni Kaliontzopoulou, a member of the Department of Evolutionary Biology, Ecology and Environmental Sciences of the UB.

    The new study combines cutting-edge analytical tools to study the evolution of phenotypes and the biogeographic history of green lizard phylogeny, and to infer their relative contribution to species diversification. The team links high-temporal resolution biogeographic models, which integrate for the first time comprehensive data on changes in terrestrial ecosystem configuration and connectivity in the Mediterranean to assess the importance of dispersal and vicariance in determining historical range dynamics.

    Specifically, the team implemented phenotypic modelling of phylogenies to identify changes in the evolutionary rate of morphological diversity and the climatic niches occupied. This information was then combined with a series of trait-dependent diversification analyses to establish how the diversification of the lineage group had been shaped.

    “Such inferences usually focus on a single aspect of diversification: either cladogenesis, geographic dynamics, climatic niche properties or phenotypic trait evolution”, Kaliontzopoulou adds. “Our study is innovative in bringing together evidence that has allowed us to contrast hypotheses about different potential evolutionary processes that might act separately or in combination to shape species diversity in the Mediterranean hotspot”.

    The study provides evidence that, when all existing diversity is considered, the biogeographic history of this emblematic group of Mediterranean lizards is the result of a combination of range expansions associated with dispersal events —probably dependent on geographic distance— and rapid evolution of ecological niche characteristics within a specific clade.

    “As a whole, the group has diversified in a relatively steady rhythm, without changes in lineage diversification rates associated to major climatic events of the Mediterranean region, and without an apparent link to functional morphological or climatic niche divergence”, says Kaliontzopolou. “Rather, the colonization of previously empty areas rather promoted the diversification of new lineages through their isolation from their relatives and was facilitated, in some groups, by an increased tolerance to lower temperatures”.

    A recurring pattern in Mediterranean ecosystems

    All indications are that the evolutionary history of green lizards was dominated by biogeographical episodes of long-distance dispersal into previously empty areas, modulated by the allopatric divergence process. These processes are also accompanied by the mechanism of ecological niche conservatism, occasionally interrupted by events of local evolution and adaptation of climatic niches, but with no signs of connection to morphological evolution.

    “Our study provides evidence of a combined role of higher-scale niche conservatism and rapid niche evolution underlying the evolutionary history of this lizard clade around the Mediterranean”, says Kaliontzopolou. “

    This seems to be established as a recurrent pattern in Mediterranean ecosystems, with several examples accumulating to support the idea that while niche conservatism is a common mechanism favoring the buildup of diversity, transition away from hotspots is related to events of accelerated niche evolution. Furthermore, diversification in functional morphology does not emerge as a key component of the diversification process of green lizards”.

    This contrasts with other biogeographic areas —perhaps with more stable climatic conditions such as the tropics— where structural niche partitioning is an important process of lineage diversification.

    “In Mediterranean ecosystems, instead, it seems that lineage diversification is rather driven by geological events and through allopatric divergence after the colonization of new environments. In such environments, morphological divergence seems to occur in much more recent times and within already diversified groups, possibly as a response to ecological-scale events or processes such as sexual selection, not investigated in our study”, concludes the researcher.

    [ad_2]

    University of Barcelona

    Source link

  • New Scottish Fossil Sheds Light on the Origins of Lizards

    New Scottish Fossil Sheds Light on the Origins of Lizards

    [ad_1]

    Newswise — A fossil discovery from Scotland has provided new information on the early evolution of lizards, during the time of the dinosaurs.

    The tiny skeleton discovered on the Isle of Skye, called Bellairsia gracilis, is only 6 cm long and dates from the Middle Jurassic, 166 million years ago. The exceptional new fossil comprises a near-complete skeleton in life-like articulation, missing only the snout and tail. This makes it the most complete fossil lizard of this age anywhere in the world.

    Bellairsia has a mixture of ancestral and modern features in its skeleton, providing evidence of what the ancestor of today’s lizards (which are part of the wider animal group known as ‘squamates’) might have looked like.

    The research, a joint project between researchers at the universities of Warsaw, Oxford and UCL, is reported in the journal Nature. First author Dr Mateusz Tałanda (University of Warsaw and UCL) said: ‘This little fossil lets us see evolution in action. In palaeontology you rarely have the opportunity to work with such complete, well-preserved fossils coming from a time about which we know so little.’

    The fossil was found in 2016 by a team led by Oxford University and National Museums Scotland. It is one of several new fossil discoveries from the island, including early amphibians and mammals, which are revealing evolution of important animal groups that persist to the present day.

    Dr Tałanda commented: ‘Bellairsia has some modern lizard features, like traits related to cranial kinesis – that’s the movement of the skull bones in relation to one another. This is an important functional feature of many living squamates.’

    Co-author Dr Elsa Panciroli (Oxford University Museum of Natural History and National Museums Scotland) who discovered the fossil, said: ‘It was one of the first fossils I found when I began working on Skye. The little black skull was poking out from the pale limestone, but it was so small I was lucky to spot it. Looking closer I saw the tiny teeth, and realised I’d found something important, but we had no idea until later that almost the whole skeleton was in there.’

    Squamates are the living group that includes lizards and snakes, and comprises more than 10,000 species today, making them one of the most species-rich living vertebrate animal groups. They include animals as diverse as snakes, chameleons, and geckos, found around the world. The group is characterised by numerous specialised features of the skull and rest of the skeleton.

    Although we know the earliest origins of squamates lie 240 million years ago in the Triassic, a lack of fossils from the Triassic and Jurassic has made their early evolution and anatomy difficult to trace.

    Analysing the new fossil alongside living and extinct fossil squamates confirms Bellairsia belongs to the ‘stem’ of the squamate family tree. This means that it split from other lizards just before the origin of modern groups. The research also supports the finding that geckos are a very early branching lineage, and that the enigmatic fossil Oculudentavis, previously suggested to be a dinosaur, is also a stem squamate.

    To study the specimen, the team used X-ray computed tomography (CT) which, like medical CT, allows for non-invasive 3D imaging. This allowed the researchers to image the entire fossil, even though most of the specimen is still hidden by surrounding rock. Whereas medical scanners work at the millimetre scale, the Oxford University CT scanner revealed details down to a few tens of micrometres.

    Parts of the skeleton were then imaged in even greater detail, including the skull, hindlimbs and pelvis, at the European Synchrotron (ESRF, Grenoble, France). The intensity of the synchrotron beam permits a resolution of 4 micrometres, revealing details of the smallest bones in the skeleton.

    Co-author Professor Roger Benson (Department of Earth Sciences, University of Oxford), said: ‘Fossils like this Bellairsia specimen have huge value in filling gaps in our understanding of evolution and the history of life on Earth. It used to be almost impossible to study such tiny fossils like this, but this study shows the power of new techniques including CT scanning to image these non-destructively and in great detail.’

    Co-author Professor Susan Evans (UCL), who first described and named Bellairsia from a few jaw and skull bones from Oxfordshire 25 years ago, added: ‘It is wonderful to have a complete specimen of this tantalising little lizard, and to see where it fits in the evolutionary tree. Through fossils like Bellairsia we are gaining a better understanding of early lizard anatomy. Angus Bellairs, the lizard embryologist after which Bellairsia was originally named, would have been delighted.’

    The study was led by Dr Mateusz Tałanda (University of Warsaw) and involved researchers from the University of Oxford’s Earth Sciences Department, Oxford University Museum of Natural History, UCL (University College London), the European Synchrotron Radiation Facility, the Natural History Museum in London and National Museums of Scotland.

    Funding was provided by the Ministry of Science and Higher Education, Poland. The John Muir Trust provided access to the Elgol Coast Site of Special Scientific Interest, and NatureScot granted permits for fossil collection.

     

    Notes to Editors

    The study will be published in Nature. The DOI number for this paper will be 10.1038/s41586-022-05332-6. Once the paper has been published online, it will be available at the following URL: https://www.nature.com/articles/s41586-022-05332-6

     

    About the University of Oxford

    Oxford University has been placed number 1 in the Times Higher Education World University Rankings for the seventh year running, and ​number 2 in the QS World Rankings 2022. At the heart of this success are the twin-pillars of our ground-breaking research and innovation and our distinctive educational offer.

    Oxford is world-famous for research and teaching excellence and home to some of the most talented people from across the globe. Our work helps the lives of millions, solving real-world problems through a huge network of partnerships and collaborations. The breadth and interdisciplinary nature of our research alongside our personalised approach to teaching sparks imaginative and inventive insights and solutions.

    Through its research commercialisation arm, Oxford University Innovation, Oxford is the highest university patent filer in the UK and is ranked first in the UK for university spinouts, having created more than 200 new companies since 1988. Over a third of these companies have been created in the past three years. The university is a catalyst for prosperity in Oxfordshire and the United Kingdom, contributing £15.7 billion to the UK economy in 2018/19, and supports more than 28,000 full time jobs.

    About UCL – London’s Global University

    UCL is a diverse global community of world-class academics, students, industry links, external partners, and alumni. Our powerful collective of individuals and institutions work together to explore new possibilities.

    Since 1826, we have championed independent thought by attracting and nurturing the world’s best minds. Our community of more than 43,800 students from 150 countries and over 14,300 staff pursues academic excellence, breaks boundaries and makes a positive impact on real world problems.

    We are consistently ranked among the top 10 universities in the world and are one of only a handful of institutions rated as having the strongest academic reputation and the broadest research impact.

    We have a progressive and integrated approach to our teaching and research – championing innovation, creativity and cross-disciplinary working. We teach our students how to think, not what to think, and see them as partners, collaborators and contributors.  

    For almost 200 years, we are proud to have opened higher education to students from a wide range of backgrounds and to change the way we create and share knowledge.

    We were the first in England to welcome women to university education and that courageous attitude and disruptive spirit is still alive today. We are UCL.

    www.ucl.ac.uk | Follow @uclnews on Twitter | Read news at www.ucl.ac.uk/news/ | Listen to UCL podcasts on SoundCloud | Find out what’s on at UCL Minds

    About the Natural History Museum

    The Natural History Museum is both a world-leading science research centre and the most-visited indoor attraction in the UK last year. With a vision of a future in which both people and the planet thrive, it is uniquely positioned to be a powerful champion for balancing humanity’s needs with those of the natural world. It is custodian of one of the world’s most important scientific collections comprising over 80 million specimens accessed by researchers from all over the world both in person and via over 30 billion digital data downloads to date. The Museum’s 350 scientists are finding solutions to the planetary emergency from biodiversity loss through to the sustainable extraction of natural resources. The Museum uses its global reach and influence to meet its mission to create advocates for the planet – to inform, inspire and empower everyone to make a difference for nature. We welcome millions of visitors through our doors each year, our website has had 17 million visits in the last year and our touring exhibitions have been seen by around 20 million people in the last 10 years. 

    [ad_2]

    University of Oxford

    Source link