'Fósseis vivos': cobras antigas vivem em Madagascar
Quinta-feira, Abril 01, 2010Ancient Snakes Living on Madagascar
ScienceDaily (Mar. 31, 2010) — "Blindsnakes are not very pretty, are rarely noticed, and are often mistaken for earthworms," admits Blair Hedges, professor of biology at Penn State University. "Nonetheless, they tell a very interesting evolutionary story." Hedges and Nicolas Vidal, of the Muséum National d'Histoire Naturelle in Paris, are co-leaders of the team that discovered that blindsnakes are one of the few groups of organisms that inhabited Madagascar when it broke from India about 100 million years ago and are still living today.
Blind snakes have been discovered to be one of the few species now living in Madagascar that existed there when it broke from India about 100 million years ago, according to a study led by Blair Hedges at Penn State University in the United Steates and Nicolas Vidal, of the Muséum National d'Histoire Naturelle in Paris. (Credit: Frank Glaw)
The results of their study will be published in the 31 March 2010 issue of the Royal Society journal Biology Letters.
Blindsnakes comprise about 260 different species and form the largest group of the world's worm-like snakes -- scolecophidians. These burrowing animals typically are found in southern continents and tropical islands, but occur on all continents except Antarctica. They have reduced vision -- which is why they are called "blind" -- and they feed on social insects including termites and ants. Because there are almost no known fossil blindsnakes, their evolution has been difficult to piece together. Also, because of their underground lifestyle, scientists have long wondered how they managed to spread from continent to continent.
In this study, the team investigated the evolution of blindsnakes by examining the genetics of living species. They extracted five nuclear genes, which code for proteins, from 96 different species of worm-like snakes to reconstruct the branching pattern of their evolution and allow the team to estimate the times of divergence of different lineages within blindsnakes using molecular clocks. "Our findings show that continental drift had a huge impact on blindsnake evolution," explains Vidal, "by separating populations from each other as continents moved apart."
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