Researchers Sequence Endangered Aye-Aye Lemur Genome
March 25, 2013

Researchers Sequence Endangered Aye-Aye Lemur Genome

Brett Smith for — Your Universe Online

A group of American and Canadian scientists has announced the complete genomic sequencing of three populations of aye-ayes, which is being considered a major victory in the battle to save the unique lemurs.

Found only on Madagascar, the aye-aye was recently was classified as "Endangered" by the International Union for the Conservation of Nature (IUCN).

"The aye-aye is one of the world's most unusual and fascinating animals," said study co-author George H. Perry, a biologist at Pennsylvania State University. "Aye-ayes use continuously growing incisors to gnaw through the bark of dead trees and then a long, thin, and flexible middle finger to extract insect larvae, filling the ecological niche of a woodpecker.

“Aye-ayes are nocturnal, solitary, and have very low population densities, making them difficult to study and sample in the wild,” he said.

To determine the genetic diversity of the different populations, the team collected aye-aye DNA samples from the northern, eastern and western regions of Madagascar. Complete genome sequences were generated from twelve individual animals.

After comparing the genomes of the three populations, the researchers found while eastern and western aye-ayes are genetically separate, eastern aye-ayes are much more genetically separate from northern aye-ayes, suggesting these two populations have not significantly interbred.

"We believe that northern aye-ayes have not been able to interbreed with other populations for some time," explained co-author Webb Miller, a professor of biology and of computer science and engineering at Penn State.  “Although they are separated by a distance of only about 160 miles, high and extensive plateaus and major rivers may have made intermingling relatively infrequent.”

The team also compared the genetic diversity of the aye-ayes to that of modern humans. To compare the two, the researchers gathered twelve complete human DNA sequences from publicly available databases for three distinct human populations: Africans, Europeans, and Southeast Asians. Their analysis found modern African and European human populations have a smaller amount of genetic distance between them than northern and eastern aye-aye populations. The team added that the two populations have been separated longer than 2,300 years, which is when human settlers first arrived on Madagascar.

The researchers said understanding the genetic diversity of the island´s aye-aye populations will be crucial to the lemur´s conservation.

"This work highlights an important region of aye-aye biodiversity in northern Madagascar, and this unique biodiversity is not preserved anywhere except in the wild," said co-author Edward Louis, Director of Conservation Genetics at Omaha, Nebraska´s Henry Doorly Zoo and Aquarium. "There is tremendous historical loss of habitat in northern Madagascar that is continuing at an unsustainable rate today. This study is an excellent example of how a comprehensive and coordinated effort in the field and laboratory can identify previously unknown patterns of biodiversity for an endangered species, which then can be used by conservation organizations to base their management strategies."

"Aye-aye population densities are very low, and individual aye-ayes have huge home-range requirements," Perry added. "As forest patches become smaller, there is a particular risk that there won't be sufficient numbers of individual aye-ayes in a given area to maintain a population over multiple generations.”