March 26, 2013
The researcher collected samples from aye-ayes in three distinct regions of regions of Madagascar: the northern, eastern and western zones. They then compared the results, finding that the aye-aye populations have been geographically separated for more than 2,300 years.
"We believe that northern aye-ayes have not been able to interbreed with other populations for some time," said study co-author Webb Miller of Penn State University. "Although they are separated by a distance of only about 160 miles, high plateaus and major rivers may have made intermingling relatively infrequent."
The genetic analysis shows that aye-ayes have more "genetic distance" than three distinct human populations: African agriculturalists, individuals of European descent, and Southeast Asian individuals.
"The level of genetic differentiation between aye-aye populations from the North and East regions of Madagascar is more than 2.1-times greater than that between human Africans and European," the authors write.
"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," added co-author Edward Louis of the Henry Doorly Zoo. "There is tremendous historical loss of habitat in northern Madagascar that's continuing at an unsustainable rate today."
Deforestation and direct persecution — in many rural communities the aye-aye is considered a harbinger of bad luck — are chief threats to the species.
Aye-aye in Madagascar. Photo by Rhett A. Butler.
The aye-aye is a particularly unusual species of primate — the nocturnal and reclusive lemur looks like it has been assembled from a variety of animals. The aye-aye resembles a large house cat but with the face of a ferret or weasel, bat-like ears capable of rotating independently, teeth that grow constantly like those of a rodent, piercing orange to green eyes, and black hands featuring a bony middle finger reminiscent of a dead twig. The aye-aye uses this finger for locating insect larvae that lurk deep inside tree bark, seeds, and fruit. As it climbs along a tree branch, the aye-aye taps the bark while listening for cavities in the wood. When it hears something potentially appetizing beneath the surface, the aye-aye gnaws away at the wood in search of its prize.
"Aye-ayes," said lead author George Perry of Penn State, "[fill] the ecological niche of a woodpecker."
The aye-aye's biology is so strange that scientists did not know what to make of the animal when it was described in 1782. Scientists first classified the aye-aye as rodent before realizing that it was just a really peculiar lemur that deserved its own family, Daubentoniidae. In the past, there was a second, larger species of aye-aye. But this species, like more than dozen other species of large lemurs, went extinct after the arrival of humans in Madagascar less than 2,000 years ago.
CITATION: George H. Perry at al. Aye-aye population genomic analyses highlight an important center of endemism in northern Madagascar. PNAS March 26, 2013. www.pnas.org/cgi/doi/10.1073/pnas.1211990110