Lemurs' evolutionary history may shed light on our own

DURHAM, N.C. -- 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.