Key Link in Turtle Evolution discovered
http://smithsonianscience.si.edu/201...on-discovered/An international team of researchers from the United States and Germany have discovered a key missing link in the evolutionary history of turtles. The new extinct species of reptile, Pappochelys, was unearthed in an area that was an ancient lake in southern Germany about 240 million years ago during the Middle Triassic. Its physical traits make it a clear intermediate between two of the earliest known turtles, Eunotosaurus and Odontochelys. Features in the skull of Pappochelys also provide critical evidence that turtles are most closely related to other modern reptiles, such as lizards and snakes. Previously, scientists believed that turtles may have descended from the earliest known reptiles. Additional information is available in the June 24 issue of Nature.
Hans-Dieter Sues, curator of vertebrate paleontology in the Department of Paleobiology at the Smithsonian’s National Museum of Natural History, and Rainer Schoch, curator of fossil amphibians and reptiles at the State Museum of Natural History in Stuttgart, Germany, studied more than a dozen specimens from Germany that were collected beginning in 2006. Their research focused on the morphological features that set Pappochelys apart from its closest turtle relatives.
“The mystery of how the turtle got its s has been a long-standing question in evolutionary biology,” said Sues. “In the case of Pappochelys, we see that its belly was protected by an array of rod-like bones, some of which are already fused to each other. Such a stage in the evolution of the turtle s had long been predicted by embryological research on present-day turtles but had never been observed in fossils—until now.”
The discovery of Pappochelys confirms that the belly portion of the turtle s , called the plastron, formed through the fusion of rib-like structures and parts of the shoulder girdle.
The new turtle is also noteworthy for the presence of two openings behind the eye socket on each side of the skull and shows that turtles did not evolve from early stem-reptiles, as traditionally thought, but are most closely related to lizards among present-day reptiles. Present-day turtles have lost these openings, but lizards and crocodilians have them.
Pappochelys could fit in the palm of a human hand and grow up to 8 inches in length. It lived in a tropical environment along the shores of a lake in what is now southern Germany. Pappochelys used its tiny, peg-like teeth to feed on small insects and worms and had a long tail, possibly to help with swimming.
The origin and relationships of turtle species have historically been some of the most contentious issues in the study of vertebrate evolution. Modern turtles are strikingly different than their prehistoric precursors, and, for decades, researchers had few representatives of the early phases of turtle evolution from the fossil record. The new discovery and DNA sequencing for the major groups of present-day reptiles now establish where turtles fit on the reptile tree of life.
Yet another intermediate form discovered.
The stickleback...
Seem to remember reading a fantastic article about speciation in S. American mountain streams at differing pool elevations, fascinating stuff.
Its so cool when nature is so much more creative than anything human beings can make up.
the varied species found in the congo river is a fascinating study.
http://www.vocativ.com/news/262022/e...volution-laws/An evolutionary biologist published a scholarly act of trolling against creationists that was a decade in the making—a phylogenetic diagram showing the evolution of anti-evolution policy. Nick Matzke finished the study just in time for the 10-year anniversary of Kitzmiller v. Dover, one of the most important legal blows against the teaching of creationism in public schools.
To build the evolutionary chart, Matzke used BEAST (Bayesian Evolutionary Analysis Sampling Trees), a program that searches through millions of possible phylogenetic tree diagrams to determine the tree with the most overlap for a particular set of data. Phylogenetic trees, also called evolutionary trees, depict the evolutionary relationship between en ies, often based on genetic or physical similarities. The software is used to study the evolution of everything from HIV to dinosaurs, but he may be the first to use it for legislation. Instead of using the program to study DNA similarities, Matzke used it to find similarities in the text of 67 anti-evolution bills introduced over the last 10 years. When the tree was complete, the results reminded Matzke of something.
“You could make a pretty good analogy between the evolution of anti-evolution policy and the evolution of variants of diseases,” Matzke told Vocativ. “Diseases often evolve to become less aggressive, because if they’re too aggressive they end up provoking an immune reaction or they kill the host. A disease that can go under the radar and hide from the immune system can spread to other people quicker.”
This parallels the way anti-evolution policy language became more subtle after aggressive bills were voted down. The study shows that legislators often reused the exact same language from past bills, only slightly modified. Matzke says early bills would have statements like: “Teachers should be allowed to teach the controversy on evolution, the origin of life and climate change.” Over time that message was softened to simply “teach the controversy.”
Matzke, who is postdoctoral fellow at the National Ins ute for Mathematical and Biological Synthesis, calls this current wave of anti-evolutionism “stealth creationism” and he asserts that is part of the reason we don’t read about creationism in the news as much. But while anti-evolution policy might be developing camouflage, Matzke doesn’t think it’s evolving intelligence. “There aren’t random mutations to these bills. It’s humans making decisions when you change something,” Matzke said. “But I think the intelligence involved is debatable. ‘Teach the controversy’—what does that even mean?”
Meanwhile, these bills only encourage teachers to misstate scientific facts or discourage students from learning “controversial science”, according to Matzke, who hopes his study will help proponents of fact-based science education to find hidden creationist agenda within bills.
SOSDDThis is just the latest chapter in a battle between the Discovery Ins ute and Matzke, a battle that goes back ten years to the 2005 federal court case Kitzmiller v. Dover, aka The Dover Panda Trial. The case revolved around a textbook, Of Pandas and People, a pseudoscience biology textbook with an intelligent design message, which the administrators at Dover Area School District in Pennsylvania wanted to use in classes. Matzke was the public information project director of the National Center for Science Education, which was providing consultation for the plaintiff, Tammy Kitzmiller and ten other parents who didn’t wanted their ninth-grade children to learn that Intelligent Design was an alternative to Darwinism.
One of the key debates at the center of the case was whether the textbook was presenting Intelligent Design—the notion that there is some complex, master intelligence guiding biology—as a possible theory, or whether it was a work of Biblically-rooted creationism. Matzke believed the latter.
“I found evidence that indicated there were creationist drafts of Of Pandas and People.” Matzke said. “The lawyer [for Kitzmiller] issued a subpoena and they got the unpublished drafts of this book. And it turned out, yep, creationist terms had been turned into intelligent-design terms [in] about a hundred [instances] before that book was published.”
Thanks largely to these drafts, the judge determined that Of Pandas and People “contains outdated concepts and flawed science,” and its use in the district’s school system was prohibited. As it turns out, the book was just another example of stealth evolution.
It wasn’t all about vertebrates this year. A 1.7 meter long 460 million year old sea scorpion was discovered in the remains of an ancient ocean in Iowa. Lead author James Lamsdell describes Pentecopterus as “incredibly bizarre”, with a strangely shaped head and paddle-like appendages. The discovery of Pentecopterus decorahensis pushes back the origin of eurypterids by 9 million years, as it is the oldest sea scorpion ever discovered.
Study: Shifting climate dictated evolution of modern birds
WASHINGTON, Dec. 14 (UPI) -- New physiological and genetic analysis suggests all modern birds are descended from a single species in South America.
The research also shows diversification was largely dictated by climatic changes, particularly widespread cooling trends beginning 91 million years ago.
Previously, researchers thought the disappearance of the dinosaurs 66 million years ago was the chief driver of diversification -- the branching off of new bird species. But the latest findings, published last week in the journal Scientific Advances, contradict this theory.
"Our results show that rapid diversification began before the mass extinction event and coinciding with a long-term cooling trend at the end of the Cretaceous," Santiago Claramunt, an ornithologist with the American Museum of Natural History, told Discovery News.
Though birds surely benefited from ecological niches left empty by the dino's downfall, the evidence suggests branches from the family tree of modern birds began radiating prior to the extinction event.
As cooling fragmented tropical environs, newly evolved bird species set out to colonize new territory, utilizing land bridges to move from South America onto other continents.
Researchers analyzed genetic data from 130 fossils representing all major bird families in order to build an evolutionary time tree, allowing scientists to pinpoint when and where modern bird lineages first emerged.
Though the evidence points to a single founding father in South America -- a species that lived alongside the dinosaurs 95 million years ago -- scientists haven't been able to determine the iden y of the mystery bird.
"It's a difficult problem to solve because we have very large gaps in the fossil record," explained Joel Cracraft, curator of the museum's ornithology department. "This is the first quan ative analysis estimating where birds might have arisen, based on the best phylogenetic hypothesis that we have today."
http://www.upi.com/Science_News/2015...8231450109101/
Plants crawled onto land earlier than we give them credit, genetic evidence suggests
Plant biologists agree that it all began with green algae. At some point in our planet's history, the common ancestor of trees and flowers developed an alternating life cycle -- allowing their offspring to conquer Earth. But now scientists argue that some green algae had been hanging out on land hundreds of millions of years before this adaptation and that land plants actually evolved from terrestrial, not aquatic, algae.
Plant biologists agree that it all began with green algae. At some point in our planet's history, the common ancestor of trees, ferns, and flowers developed an alternating life cycle--presumably allowing their offspring to float inland and conquer Earth. But on December 16 in Trends in Plant Science, Danish scientists argue that some green algae had been hanging out on land hundreds of millions of years before this adaptation and that land plants actually evolved from terrestrial, not aquatic, algae.
Botanists have suspected this possibility since 1980, but supporters have lacked proof. Now, Carlsberg Laboratory's Jesper Harholt and University of Copenhagen's Øjvind Moestrup and Peter Ulvskov present genetic and morphological evidence that corroborates the theory. Notably, traits that land plants use to survive on land today are well conserved in some species of green algae.
...
http://www.sciencedaily.com/releases...1216134406.htm
Study... after study... after study...
Meanwhile Avante has abandoned his own evolution thread, preferring to talk about just about anything else.
Creationism evangelist: God put contradictions in the Bible to ‘weed out’ the atheists
Young Earth creationism evangelist Kent Hovind asserted this week that that God had purposefully put contradictions in the Bible to “weed out” non-believers.In a YouTube video posted on Monday, the Christian fundamentalist responds to a follower who is troubled by a contradiction in the book of Acts.
“If I was God,” Hovind explains, “I would write the book in such a way that those who don’t want to believe in me anyway would think they found something. ‘Aha, here’s why I don’t believe.'”
“And then they could go on with their own life because they don’t want to believe Godanyways,” he continues. “I would put things in there that would appear without digging to be contradictions. I don’t think that’s deceptive, I think that’s wise for the Heavenly Father to weed out those who are really serious.”
http://www.rawstory.com/2015/12/crea...e+Raw+Story%29
New genes born by accident lead to evolutionary innovation
Novel genes are continuously emerging during evolution, but what drives this process? A new study, published in PLOS Genetics, has found that the fortuitous appearance of certain combinations of elements in the genome can lead to the generation of new genes. This work was led by Jorge Ruiz-Orera and Mar Albà from Hospital del Mar Medical Research Ins ute in Barcelona (IMIM-ICREA).
In every genome, there are sets of genes, which are unique to that particular species. In this study, the scientists first identified thousands of genes that were specific to human or chimpanzee. Then, they searched the macaque genome and discovered that this species had significantly less element motifs in the corresponding genomic sequences. These motifs are recognized by proteins that activate gene expression, a necessary step in the formation of a new gene.
The formation of genes de novo from previously non-active parts of the genome was, until recently, considered highly improbable.
This study has shown that the mutations that occur normally in our genetic material may be sufficient to explain how this happens. Once expressed, the genes can act as a substrate for the evolution of new molecular functions. This study identified several candidate human proteins that bear no resemblance to any other known protein. What they do is an enigma still to be resolved.
http://www.eurekalert.org/pub_releas...-ngb123015.php
Team identifies ancient mutation that contributed to evolution of multicellular animals
Molecular time travel experiments reveal a simple genetic basis for the evolution of a protein necessary for multicellularity, one billion years ago
A single chance mutation about a billion years ago caused an ancient protein to evolve a new function essential for multicellularity in animals, according to new research co-led by a University of Chicago scientist. By conducting experiments on 'resurrected' ancestral proteins, the researchers shed light on the origin of a molecular process that allows animals to form and maintain organized tissues.
The study, published in the journal eLife on Jan. 7, 2016, is the first to experimentally describe a molecular mechanism involved in the evolution of multicellularity, and it establishes a paradigm for research in evolutionary cell biology and the origins of complex life.
"Our experiments show how biological complexity can evolve though simple, high-probability genetic paths," said the study's co-senior author Joe Thornton, PhD, professor of human genetics and ecology and evolution at the University of Chicago. "Before the last common ancestor of all animals, when only single-celled organisms existed on Earth, just one tiny change in DNA sequence caused a protein to switch from its primordial role as an enzyme to a new function that became essential to organize multicellular structures."
Few events in the history of life on Earth are as significant as the evolution of multicellular animals from single-celled ancestors. Multicellularity depends on a suite of cellular interactions and molecular functions, but almost nothing is known about how those functions evolved.
Thornton and his colleagues focused on a process called mitotic spindle orientation. To form and maintain organized tissues, cells must orient the direction in which they divide relative to their neighbors. In the flat tissues that line organs, for example, cells divide within the plane of the tissue; otherwise, malformations and cancer can result. Cells accomplish this through a structure called the mitotic spindle -- a network of protein filaments that pulls freshly duplicated chromosomes to opposite ends of the cell before it splits into two.
In cells from a broad range of animal species, the spindle is rotated relative to surrounding cells by a protein scaffold known as the guanylate kinase protein interaction domain (GK-PID). It acts as a kind of molecular carabiner by binding to two different partner molecules: an 'anchor' protein on the inside of the cell membrane that indicates the position of adjacent cells and a motor protein that pulls on mitotic spindle filaments. Once hooked together by GK-PID, the motors pull the chromosomes toward the anchors, orienting new daughter cells in line with neighboring cells.
Molecular time travel
To study how GK-PID evolved its function as a spindle-orienting carabiner, Thornton and his colleagues used ancestral protein reconstruction -- a technique Thornton's group pioneered -- to experimentally retrace the evolution of genes and proteins by working backwards through the tree of life.
Graduate students Doug Anderson and Victor Hanson-Smith first used computational methods to reconstruct the evolutionary histories of GK-PID and a related enzyme known as guanylate kinase (gk). The two proteins share similarities in sequence and structure but have different functions and histories -- GK-PID is found in only animals and their closest unicellular relatives, while gk plays a fundamental role in making the components of DNA and is universal to life.
Their analysis revealed that GK-PID evolved when the gene for the gk enzyme duplicated and then began to diverge. This event occurred before animals and their closest unicellular relatives split from other single-celled organisms, roughly a billion years ago. One copy retained its original function, but the other evolved the capacity to serve as a molecular carabiner in spindle orientation.
The team reconstructed the ancient forms of gk and GK-PID to study how this transition occurred. Working backwards from hundreds of present-day species, they used sophisticated computational methods to infer ancestral genetic sequences from the time that the GK-PID first appeared. With study co-leader Ken Prehoda at the University of Oregon, the researchers chemically synthesized the ancestral genes and inserted them into bacterial and insect cells, which produced the proteins as they existed in the distant past.
The most ancient progenitor protein, which existed just before the duplication that produced GK-PID, functioned as an enzyme. But the researchers found that they could recapitulate evolution by introducing a single mutation, which switched the protein's function, abolishing its enzyme activity and conferring the ability to act as a carabiner that could bind the anchor protein.
Remarkably, when this slightly altered version of a one billion-year-old protein was inserted into cultured insect cells -- which had their present-day GK-PID proteins disabled and therefore could not carry out spindle orientation -- the cells became able to properly rotate their spindles relative to their neighbors.
"Our experiments show that the GK-PID evolved its carabiner function early, before multicellularity itself appeared," Thornton said. "That one ancient mutation yielded a wholly new molecular function, which helped set the stage for multicellular animals to eventually evolve."
What's old is new again
The team also investigated the evolution of the anchor proteins to which GK-PID attaches. Surprisingly, these proteins first appeared in the lineage leading to animals, suggesting that GK-PID gained its ability to bind to the anchor long before the anchor itself evolved.
Why would a protein evolve the ability to bind to something that wouldn't appear for millions of years? A deeper analysis of the proteins' structural biology suggested that the answer lies in a process that Thornton calls molecular exploitation, in which a new molecule (in this case the anchor) fortuitously binds an old protein (GK-PID) because it just happens to be structurally similar to the protein's original molecular partner.
The researchers found that the ancestral GK-PID bound the anchor protein in a very similar way to how the ancestral gk enzyme bound its substrate. This region could bind both partners because the key portion of the anchor protein happened to have a similar shape and pattern of electrical charges as the ancient enzyme substrate did. The crucial mutation in the ancestral gk protein exposed the binding surface without changing it, giving the anchor protein easier access.
"It's just coincidence that the two molecules look so similar," Thornton said. "But that lucky resemblance is why a simple genetic event could cause the evolution of a molecular partnership that is now essential to the biology of complex animals."
The group's findings provide the first detailed molecular explanation for the evolution of functions involved in multicellularity and complex life. Thornton points out that many key steps in the evolution of spindle orientation remain to be reconstructed, and still more questions are unanswered concerning the evolution of other functions that made multicellularity possible. The study of GK-PID now shows one way that the emerging scientific field of evolutionary cell biology might answer those questions.
"We hope that the approach we used -- reconstructing in detail the ancient history of protein functions -- can be applied to the evolution of other key cellular processes, revealing the whole picture of multicellular life evolving from single-celled ancestors," Thornton said.
###
The study, "Evolution of an ancient protein function involved in organized multicellularity in animals," was supported by the National Ins utes of Health (R01GM104397, R01GM087457, R01GM089977) and a Howard Hughes Medical Ins ute Early Career Scientist Award to Thornton. Additional authors include Arielle Woznicka and Nicole King from the University of California, Berkeley, William Campodonico-Burnett from the University of Oregon, and Dustin Whitney and Brian Volkman from the Medical College of Wisconsin.
A large phylogenomics study reveals that the symbiotic event that led to the emergence of organelles known as mitochondria may have occurred later in the evolution of complex cells than was thought.
http://www.nature.com/nature/journal...ture16876.html
Team sheds light on a crucial moment in the evolution of life: when cells acquired mitochondria
Just as physicists comprehend the origin of the universe by observing the stars and archeologists reconstruct ancient civilizations with the artifacts found today, evolutionary biologists study the diversity of modern-day species to understand the origin of life and evolution.
In a study published in the prestigious magazine Nature, Centre for Genomic Regulation researchers Toni Gabaldón and Alexandros Pitis are shedding light on one of the most crucial milestones in the evolution of life: cells' acquisition of mitochondria.
The first living beings were single-cell organisms, predecessors of the bacteria that inhabit the world today. Those cells were quite simple but, at some point over the course of evolution, they gave way to a more complex cellular lineage: the eukaryotes, or cells with a nucleus. Eukaryotic cells have given rise to the most complex life forms existing on earth, including multicellular organisms such as animals, plants or fungi. One of the keys of this complexity can be found in mitochondria, a cellular organelle considered to be the generator of cell energy, although that is not their only role. It is believed that by acquiring mitochondria, cells were able to use more energy, facilitating qualitative leaps in their structure and organization. That is why the addition of mitochondria is considered a crucial milestone in the evolution of life.
Up until now, a number of theories have sought to explain how cells came to acquire mitochondria. Although there is consensus as to the "how" ?the first mitochondria must have been a bacterium that entered another, and remained there, becoming part of the cell? the "when" has so far been unclear. Some scientists advocated an early incorporation of mitochondria, and considered that step as the first necessary to begin advancing toward eukaryotic cells as they are known today. Other theories proposed a later inclusion of mitochondria, as a more complex host cell could favor the entry of another cell and that cell's permanence within its interior. Now, predoctoral scientist Alexandros Pitis and ICREA research professor and group leader at CRG Toni Gabaldón have clarified the matter, proposing a theory that would define the time frame for the acquisition.
"Like archeologists, we are trying to reconstruct something that existed in the past based on the evidence we have today. Specifically, we've tracked down proteins common to all complex organisms, and reconstructed their evolution. We found that the proteins related with mitochondria acquisition arrived later than those related with other parts of the cell," states the study's principal investigator, Toni Gabaldón. The scientists used a diverse set of measurements to date the incorporation of several proteins into the eukaryotic lineage.
They found that the arrival of proteins had come in a number of "waves", and that those related with ancestral mitochondria matched those of the latest wave. "Our work demonstrates that the acquisition of mitochondria occurred late in cell evolution, and that the host cell already had a certain degree of complexity," states Alexandros Pitis, lead author of the study. "Our study makes it possible to break down the steps of what is considered the greatest evolutionary leap after the origin of life. Understanding how complexity originated and evolved is important to better understand the mechanisms that govern cells, and by extension, the functioning of all living organisms," concludes Gabaldón.
Explore further: How did complex life evolve? The answer could be inside out
More information: Late acquisition of mitochondria by a host with chimaeric prokaryotic ancestry, DOI: 10.1038/nature16941
Read more at: http://phys.org/news/2016-02-team-cr...-life.html#jCp
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