Lemur's evolutionary history may shed light on our own

After swabbing the cheeks of more than 200 lemurs and related primates to collect their DNA, researchers at the Duke Institute for Genome Sciences & Policy (IGSP) and Duke Lemur Center now have a much clearer picture of their evolutionary family tree.

Found in nature only on the island nation of Madagascar, off Africa’s southeastern coast, lemurs and their close relatives the lorises represent the sister lineage to all other primates. And that makes lemurs key to understanding what distinguishes us and the rest of our primate cousins from all other animals, according to Julie Horvath, a post-doctoral researcher in the IGSP.

“If we find a trait or characteristic shared between lemurs and other primates, it can tell us what is or isn’t primate-specific and when those traits arose,” said Horvath, who works in the laboratory of IGSP director Huntington Willard.

The new “phylogenomic toolkit” the researchers developed will also play into conservation efforts aimed to save the critically endangered lemurs, by helping to define the number of existing species, said David Weisrock, a post-doctoral researcher working with Duke Lemur Center Director Anne Yoder.

The researchers report their findings in the March 1 issue of Genome Research.

Scientists uncover evolutionary relationships among species based on similarities and differences in their genetic codes. The increasing number of fully sequenced genomes available for major evolutionary groups has allowed resolution of relationships that had been considered unmanageable before.

But except for humans’ close evolutionary ties to chimpanzees, many of the relationships among other apes, monkeys and pre-monkeys called prosimians have remained somewhat murky, according to Horvath.

To find out where Madagascar’s lemurs fit in, the Duke team first needed to develop the tools for comparing sequences from the many lemur species to one another, and to those of other primates including humans.

The researchers identified stretches of DNA sequence held in common between the genomes of the human, the ringtailed lemur and the mouse lemur. These "conserved sequences" served as primers, allowing them to sample comparable bits of sequence across the genomes of the various primate species.

Their analysis confirmed that the first to branch off from the rest of the lemurs, some 66 million years ago, was the aye-aye--a nocturnal primate that taps on trees with its fingers to listen for insects inside, making it Madagascar’s version of a woodpecker. They also resolved the relationships among species within the remaining four evolutionary lineages, which includes a diverse cast of characters: the sifakas, named for the hissing “shee-fak” sound they make; the sportive lemurs, which are strictly nocturnal; the mouse lemurs, the smallest of all living primates; and the many so-called “true lemurs,” including the blue-eyed black lemur (one of only three blue-eyed primates in the world) and the ringtailed lemur, which is often found in zoos.

“By throwing this much data at the problem, we have absolutely confirmed, beyond any statistical doubt, that the spectacular array of lemurs all descended from a single ancestral species,” said Yoder, noting that lemurs account for about 20 percent of primate species and live on less than one percent of the earth’s surface. “It further highlights the importance of Madagascar as a cradle for biodiversity.”

The study lays the groundwork for doing future studies of lemurs and other primates. The methods the group developed for this study can also be applied to understanding evolutionary relationships among other animal groups for which genomic sequences are hard to come by.

Source: Duke University

Related stories:

It started with a squeak: Moonlight serenade helps lemurs pick mates of the right species
Lonely hearts columns testify that finding a partner can be hard enough, but at least most human beings can be fairly certain that when we do we have got one of the right species. Things aren’t so simple for all animals. Some Malagasy mouse lemurs are so similar that picking a mate of the right species, especially at night time in a tropical forest, might seem like a matter of pot luck. However, new research in BioMed Central’s journal BMC Biology has shown that our desperately cute distant cousins use vocalisations to pick up a partner of the right species.
Ancient DNA Confirms Single Origin of Malagasy Primates
Yale biologists have managed to extract and analyze DNA from giant, extinct lemurs, according to a Yale study published in a recent issue of the Proceedings of the National Academy of Sciences.
Radiocarbon dating of the bones and teeth from which the DNA was obtained reveal that each of the individuals analyzed died well over 1,000 years ago, according to the senior author, Anne Yoder, associate professor in the Department of Ecology and Evolutionary Biology.
New population of highly threatened greater bamboo lemur found in Madagascar
Researchers in Madagascar have confirmed the existence of a population of greater bamboo lemurs more than 400 kilometers (240 miles) from the only other place where the Critically Endangered species is known to live, raising hopes for its survival.
Big brains arose twice in higher primates
After taking a fresh look at an old fossil, John Flynn, Frick Curator of Paleontology at the American Museum of Natural History, and colleagues determined that the brains of the ancestors of modern Neotropical primates were as small as those of their early fossil simian counterparts in the Old World. This means one of the hallmarks of primate biology, increased brain size, arose independently in isolated groups—the platyrrhines of the Americas and the catarrhines of Africa and Eurasia.
Primate's scent speaks volumes about who he is
Perhaps judging a man by his cologne isn't as superficial as it seems.Duke University researchers, using sophisticated machinery to analyze hundreds of chemical components in a ringtailed lemur's distinctive scent, have found that individual males are not only advertising their fitness for fatherhood, but also a bit about their family tree as well.
How humans make up for an 'inborn' vitamin C deficiency
A new study appears to explain how humans, along with other higher primates, guinea pigs and fruit bats, get by with what some have called an “inborn metabolic error”: an inability to produce vitamin C from glucose.
Lemur's Little Finger Poses a Mystery
Analysis of the first hand bones belonging to an ancient lemur has revealed a mysterious joint structure that has scientists puzzled.
New satellite imaging research could save the lemur in Madagascar
New satellite imaging research may help save the dwindling lemur population in the African nation of Madagascar.

News discussion:

General Science news