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Morphological correlates of incipient arboreality and ornithophagy in island pitvipers, and the phylogenetic position of Bothrops insularis

Published online by Cambridge University Press:  27 April 2005

Wolfgang Wüster
Affiliation:
School of Biological Sciences, University of Wales, Bangor LL57 2UW, Wales, U.K.
Marcelo R. Duarte
Affiliation:
Laboratório de Herpetologia, Instituto Butantan, Av. Vital Brazil 1500, 05503-900 São Paulo-SP, Brazil
Maria da Graça Salomão
Affiliation:
Laboratório de Herpetologia, Instituto Butantan, Av. Vital Brazil 1500, 05503-900 São Paulo-SP, Brazil
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Abstract

Morphological differences between two semi-arboreal, bird-eating island pitvipers, Bothrops insularis and Gloydius shedaoensis, and their mainland relatives were investigated. Mitochondrial DNA sequence data for two genes show B. insularis to be rooted within B. jararaca. Bothrops insularis has a more anterior heart, a relatively longer tail, a longer head, and shorter fangs than B. jararaca. The greater head length is paralleled in the ecologically similar G. shedaoensis. Increased head size may represent an adaptation to the abundance of larger food items (migratory passerine birds), providing a selective advantage to snakes able to switch to larger prey at an earlier age. Furthermore, B. insularis and G. shedaoensis have converged on similar body sizes from opposite ancestral states. Other characters, including fang length, tail length and size of neonates do not show parallel variation in G. shedaoensis and B. insularis, suggesting that caution is required when interpreting character state shifts coinciding with ecological shifts in a single species only.

Type
Research Article
Copyright
2005 The Zoological Society of London

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