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)
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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Biology Letters
Blindsnake evolutionary tree reveals long history on Gondwana
Nicolas Vidal1,*, Julie Marin1, Marina Morini1, Steve Donnellan2,3,William R. Branch4, Richard Thomas5,
Miguel Vences6, Addison Wynn7, Corinne Cruaud8 and S. Blair Hedges9,*
-Author Affiliations
1Département Systématique et Evolution, UMR 7138, C.P. 26, Muséum National d'Histoire Naturelle, 57 rue Cuvier, F-75231 Paris cedex 05, France
2South Australian Museum, North Terrace, Adelaide 5000, Australia
3Australian Centre for Evolutionary Biology and Biodiversity, University of Adelaide 5005, Australia
4Bayworld, PO Box 13147, Humewood 6013, South Africa
5Department of Biology, University of Puerto Rico, San Juan, Puerto Rico 00931-3360, USA
6Zoological Institute, Technical University of Braunschweig, Spielmannstr. 8, 38106 Braunschweig, Germany
7Department of Vertebrate Zoology, National Museum of Natural History, Smithsonian Institution, Washington, DC 20560-0162, USA
8Centre National de Séquençage, Genoscope, 2 rue Gaston-Crémieux, CP5706, 91057 Evry cedex, France
9Department of Biology, 208 Mueller Lab, Pennsylvania State University, University Park, PA 16802-5301, USA
*Authors for correspondence (nvidal@mnhn.fr; sbh1@psu.edu).
Abstract
Worm-like snakes (scolecophidians) are small, burrowing species with reduced vision. Although largely neglected in vertebrate research, knowledge of their biogeographical history is crucial for evaluating hypotheses of snake origins. We constructed a molecular dataset for scolecophidians with detailed sampling within the largest family, Typhlopidae (blindsnakes). Our results demonstrate that scolecophidians have had a long Gondwanan history, and that their initial diversification followed a vicariant event: the separation of East and West Gondwana approximately 150 Ma. We find that the earliest blindsnake lineages, representing two new families described here, were distributed on the palaeolandmass of India+Madagascar named here as Indigascar. Their later evolution out of Indigascar involved vicariance and several oceanic dispersal events, including a westward transatlantic one, unexpected for burrowing animals. The exceptional diversification of scolecophidians in the Cenozoic was probably linked to a parallel radiation of prey (ants and termites) as well as increased isolation of populations facilitated by their fossorial habits.
biogeography squamates snakes dispersal vicariance
Footnotes
Received March 3, 2010.
Accepted March 8, 2010.
© 2010 The Royal Society
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