Brett Smith for redOrbit.com – Your Universe Online
Thanks to an extensive research effort by a large international team, endangered monkeys in the Amazon have been found to be much more diverse than previously thought.
The results of the large research campaign culminated in a more comprehensive picture of the evolution of South American monkeys, according to a number of papers published in a special edition of the journal Molecular Phylogenetics and Evolution.
“This collection of papers is a major step toward understanding the evolutionary history and biogeographic history that have given rise to the species that we see in South American today, and it will play a key role in identifying conservation priorities for species,” said study author Michael Alfaro, a UCLA associate professor of ecology and evolutionary biology.
One of the biggest finds was that a small population of black-headed squirrel monkeys is actually a subspecies of a different species, or possibly its own species. The study team based their conclusion on a genetic analysis that found the monkey branched off from a similar group called Saimiri ustus, about 500,000 years ago and a group called Saimiri boliviensis about 1.3 million years ago.
“We found strong evidence that it’s a distinct, separate species,” said study author Jessica Lynch Alfaro, an anthropologist at UCLA’s Institute for Society and Genetics. “It’s its own unique group.”
Lynch Alfaro went on to say the find was particularly important in light of the fact that these monkeys are believed to be under threat from climate change.
“They may lose all of their habitat,” she said. “This species has the smallest, most restricted habitat of any Amazonian primate, and it has been predicted that the habitat may be drastically altered due to changes in weather patterns as a result of global warming.”
Another study published in the journal’s special edition found that to primate groups, small-bodied tamarins and large-bodied tamarins, split geographically and genetically around 9 million years ago, evolved independently and came back together around 5 million years later. The study ultimately concluded that these groups are more distinct than scientists previously thought.
“They are unique and genetically distinct,” Lynch Alfaro said. “Humans are more closely related to chimpanzees than small tamarins are to large tamarins.”
In addition to being genetically distinct, the two primate groups have different behaviors from each other. For example, large tamarins stalk their insect prey, while small tamarins look for bugs under leaves and tree bark.
UCLA researchers who worked on the team noted that the large body of research expands on the work of Alfred Russel Wallace, an early 20th century anthropologist currently being celebrated by the California university.
“We’re following in his footsteps,” Alfaro said. “He’s overshadowed by Darwin, but if there were no Darwin, everyone would be talking about Wallace.”
Testing one of Wallace’s hypotheses directly, the UCLA scientists found that large rivers feeding the Amazon are a source of diversity by compared tissue samples from primates gathered on either side of Brazil’s Rio Negro. They saw they primates on either side of the river are indeed significantly genetically different.
“They’re distinctly different because the river isolated them on either side when it formed,” Lynch Alfaro said.
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