New research shakes up the sloth family tree

JUNE 6, 2019

by American Museum of Natural History

New studies by two research teams published today in the journals Nature Ecology and Evolution and Current Biology challenge decades of accepted scientific opinion concerning the evolutionary relationships of tree sloths and their extinct kin. The research teams used different molecular tools—the protein collagen in one case and the mitochondrial genome in the other—but they reached nearly the same results. The concurrent findings are significant because they provide molecular evidence that appears to overturn a longstanding consensus, based on the study of anatomical features, regarding how the major groups of sloths are related to one another.

Corresponding authors Ross D. E. MacPhee of the American Museum of Natural History and Frédéric Delsuc of the French National Centre for Scientific Research (CNRS) at the University of Montpellier noted that, although their research groups worked separately, they were in communication.

"All of us were initially surprised by our results because they thoroughly contradicted what seemed to be the accepted view based on anatomy," said Delsuc.

"Exceptional results demand exceptional verification," continued MacPhee, a curator in the Museum's Department of Mammalogy, "That's why we arranged with the journals to publish our papers simultaneously, to emphasize that corroboration is a crucial part of good science."

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Crabs, lobsters and shrimp now have a family tree dating 500 million years

APRIL 24, 2019

by Chrystian Tejedor, Florida International University

Researchers have for the first time traced the roots of crabs, lobsters and shrimp to create the family tree of crustaceans people love to eat.

The tree shows the 450-million-year evolution of these 10-legged decapods, when lobsters and crabs each diversified from a single evolutionary origin. Groups of shrimpevolved earlier.

The findings are part of a massive family tree project where researchers resolved the deep evolutionary relationships between crabs, shrimp and lobsters. The discoveries made by analyzing more than 400 genes from 94 species could also inform conservation policies to ensure their longevity.

"Understanding the origins of biodiversity across half a billion years in groups that are extremely ecologically and economically important is fascinating," said FIU marine sciences professor Heather Bracken-Grissom, the anchor author of the study. "This is extremely important since studying and preserving biodiversity needs to be at the forefront of our efforts in the biological sciences and across humanity"

The boom of diversification for crabs, lobsters and shrimp may coincide with the spread of modern reef-building corals, Bracken-Grissom said. It is possible the emergence of reef-building corals provided new habits for decapods to colonize and diversify, leading to the emergence of several new lineages after the mass extinction of life on Earth 250 million years ago.

While the study produced the largest amount of genetic information about decapods, more work remains to be done including the addition of more species to better understand species-level relationships. The researchers hope the newly generated genomic resources will be used by others interested in decapod crustaceans for years to come.

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Genetic study shakes up the elephant family tree

Date: June 6, 2017

Source: University of Illinois at Urbana-Champaign

New research reveals that a species of giant elephant that lived 1.5 million to 100,000 years ago -- ranging across Eurasia before it went extinct -- is more closely related to today's African forest elephant than the forest elephant is to its nearest living relative, the African savanna elephant.

The study challenges a long-held assumption among paleontologists that the extinct giant, Palaeoloxodon antiquus, was most closely related to the Asian elephant. The findings, reported in the journal eLife, also add to the evidence that today's African elephants belong to two distinct species, not one, as was once assumed.

Understanding their genetic heritage is key to keeping today's elephants from going extinct, said University of Illinois animal sciences professor Alfred Roca, a co-author of the new study. Roca led research in the early 2000s that provided the first genetic evidence that African elephants belonged to two distinct species. Subsequent studies have confirmed this, as does the new research.

"We've had really good genetic evidence since the year 2001 that forest and savanna elephants in Africa are two different species, but it's been very difficult to convince conservation agencies that that's the case," Roca said. "With the new genetic evidence from Palaeoloxodon, it becomes almost impossible to argue that the elephants now living in Africa belong to a single species."

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Family tree of dogs reveals secret history of canines

By Helen Briggs BBC News

25 April 2017

The largest family tree of dogs ever assembled shows how canines evolved into more than 150 modern breeds.

Dogs were first selected and bred for their ability to perform tasks such as herding goats or cattle, say scientists.

Later, they were selected for physical features such as their size or colour.

The study also unearths evidence that some dogs are descended from an ancient breed that travelled with the ancestors of Native Americans into the Americas.

Archaeological evidence points to the so-called "New World dog", which apparently crossed with human settlers over a land bridge from Asia.

It had previously been thought that all signs of this ancient breed had been erased as dogs bred in Europe spread around the world.

"We think there is still some signature of New World dog hiding in the genome of some of these American breeds," said co-researcher Heidi Parker of the National Institutes of Health, US.

Modern hairless breeds such as the Peruvian hairless dog and the Mexican hairless dog are likely descended from this ancient dog.

 

Read on 

Rooting the family tree of placental mammals

 February 15, 2016

Placental mammals consist of three main groups that diverged rapidly, evolving in wildly different directions: Afrotheria (for example, elephants and tenrecs), Xenarthra (such as armadillos and sloths) and Boreoeutheria (all other placental mammals). The relationships between them have been a subject of fierce controversy with multiple studies coming to incompatible conclusions over the last decade leading some researchers to suggest that these relationships might be impossible to resolve.

There are thus many outstanding questions such as which is the oldest sibling of the three? Did the mammals go their separate ways due to South America and Africa breaking apart? And if not, when did placentals split up?

"This has been one of the areas of greatest debate in evolutionary biology, with many researchers considering it impossible to resolve," said lead author Dr Tarver of Bristol's School of Earth Sciences. "Now we've proven these problems can be solved - you just need to analyse genome-scale datasets using models that accurately reflect genomic evolution."

The researchers assembled the largest mammalian phylogenomic dataset ever collected before testing it with a variety of models of molecular evolution, choosing the most robust model and then analysing the data using several supercomputer clusters at the University of Bristol and the University of Texas Advanced Computing Centre. "We tested it to destruction," said Dr Tarver. "We threw the kitchen sink at it."

"A complication in reconstructing evolutionary histories from genomic data is that different parts of genomes can and often do give conflicting accounts of the history," said Dr Siavash Mirarab at the University of California San Diego, USA. "Individual genes within the same species can have different histories. This is one reason why the controversy has stood so long - many thought the relationships couldn't be resolved."

To address the complexities of analysing large numbers of genes shared among many species, the researchers paired two fundamentally different approaches - concatenated and coalescent-based analyses - to confirm the findings. When the dust settled, the team had a specific family tree showing that Atlantogenata (containing the sibling groups of African Afrotheria and the South American Xenarthra) is the sister group to all other placentals.

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'Extinct' No Longer? Brontosaurus May Make a Comeback

by Stephanie Pappas, Live Science Contributor | April 07, 2015 07:27am ET

The Brontosaurus is back. Or at least it should be, according to a new analysis of the long-necked dinosaur family tree.

The study researchers suggest the dinosaur currently known as Apatosaurus excelsus is different enough from its Apatosaurian kin as to be a different dinosaur altogether. Because A. excelsus was famously first known as Brontosaurus until 1903, the species would revert back to that original name and become Brontosaurus once again.

It's a proposal that excites some paleontologists and leaves others skeptical, but researchers say it's entirely possible that Brontosaurusmay eventually regain its place in the scientific nomenclature.

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Biologist Maps the Family Tree of All Known Snake and Lizard Groups

May 8, 2013 — A George Washington University biologist and a team of researchers have created the first large-scale evolutionary family tree for every snake and lizard around the globe. 

The findings were recently published in the journal BMC Evolutionary Biology. Alex Pyron, the Robert F. Griggs Assistant Professor of Biology in GW's Columbian College of Arts and Sciences, along with researchers from the City University of New York and Arizona State University, detail the cataloging of 4,161 species of snakes and lizards, or squamates. 

"Squamates include all lizards and snakes found throughout the globe, including around 9,500 species on every continent except Antarctica, and found in most oceans," said Dr. Pyron. "This is everything from cobras to garter snakes to tiny geckos to the Komodo Dragon to the Gila Monster. They range from tiny threadsnakes that can curl up on a dime to 10 feet monitor lizards and 30 foot pythons. They eat everything from ants to wildebeest." 

The evolutionary family tree, or phylogeny, includes all families and subfamilies and most genus and species groups, said Dr. Pyron. While there are gaps on some branches of the tree, the structure of the tree goes a long way toward fully mapping every genus and species group. 

Continued: http://www.sciencedaily.com/releases/2013/05/130508172227.htm