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 Madagascars 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 earths 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.
|Contact: Kendall Morgan|