Researchers traces ancestry of lemurs to other primates

Adding another branch to the tree of life, researchers at the Institute for Genome Sciences and Policy and the Duke Lemur Center have mapped the evolutionary family tree of lemurs, researchers announced recently. Among other uses, the new research will give scientists a better evolutionary understanding about how lemurs relate to humans. In the study, the researchers focused on lemurs from Madagascar, a group of primates whose evolutionary relationship with other primates has been a matter of controversy until recently, Dr. Julie Horvath, a postdoctoral researcher at the IGSP, wrote in an e-mail. Collaborating with scientists at the National Evolutionary Synthesis Center, Duke researchers performed phylogenetic analysis on the lemurs to map the evolutionary development and origins of a species, DLC Director Anne Yoder said. "We developed ways to gather large amounts of DNA-sequence data from many different regions of the lemur genome," David Weisrock, a postdoctoral researcher working with Yoder, wrote in an e-mail. "The differences in DNA sequence between species were then analyzed to generate a phylogenetic tree that resolves the relationships among lemur species." Species with more identical sequences are likely to share a common ancestor more recently in the evolutionary line, Horvath said. "Our study verified that all lemurs descended from a single common ancestor and that the Aye-Aye was the first lemur to diverge from the remaining lemurs," Horvath added. This process of phylogenetic analysis has shed light on where a certain primate characteristic falls on the family tree, allowing researchers to determine when a species diverged from other groups. "Researchers can now confidently say that lemurs are the closest relatives to monkeys, apes and humans," Yoder said. "Whenever you find a characteristic in lemurs that is shared with monkeys, apes or humans, then you can say that that was characteristic of the ancestral primate." Yoder added that if humans have some characteristics that lemurs do not, researchers will know that the characteristic evolved more recently and can go further down the tree to see at what point that characteristic evolved. The study was possible because of researchers' unique approach of gathering data from a large genetic sample. "This is the most comprehensive analysis of lemur phylogeny to date," Weisrock said. "All previous attempts at using molecular data to resolve lemur relationships was based on just one or a few genes and provided poor resolution or support for relationships." These findings will not only prove useful for primatologists involved in evolutionary and genetic analysis, but they also have conservation implications as well. "We want to identify existing species, which are distinct evolutionary units, because if the forest contains a unique primate species, that gives you a lot of political ammunition," Yoder said. If there is diminishing genetic variation within a species, it indicates that the species' numbers are also dwindling, she said. "Within a few years, and partly because of this research, we will know with as much certainty as we can have, what are the relationships between all living primates," Yoder said. "We can start tenting down where evolutionary novelties occurred within the primates, and from there you can distinguish what characteristics are absolutely unique to humans."