Open AccessThe origin of snakes (Serpentes) as seen through eye anatomy
Author(s) -
CAPRETTE CHRISTOPHER L.,
LEE MICHAEL S. Y.,
SHINE RICHARD,
MOKANY ALLIE,
DOWNHOWER JERRY F.
Publication year - 2004
Publication title -
biological journal of the linnean society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.906
H-Index - 112
eISSN - 1095-8312
pISSN - 0024-4066
DOI - 10.1111/j.1095-8312.2003.00305.x
Subject(s) - fossorial , biology , vertebrate , taxon , adaptation (eye) , zoology , phylogenetic tree , ecology , evolutionary biology , nocturnal , biochemistry , neuroscience , gene
Snakes evolved from lizards but have dramatically different eyes. These differences are cited widely as compelling evidence that snakes had fossorial and nocturnal ancestors. Their eyes, however, also exhibit similarities to those of aquatic vertebrates. We used a comparative analysis of ophthalmic data among vertebrate taxa to evaluate alternative hypotheses concerning the ecological origin of the distinctive features of the eyes of snakes. In parsimony and phenetic analyses, eye and orbital characters retrieved groupings more consistent with ecological adaptation rather than accepted phylogenetic relationships. Fossorial lizards and mammals cluster together, whereas snakes are widely separated from these taxa and instead cluster with primitively aquatic vertebrates. This indicates that the eyes of snakes most closely resemble those of aquatic vertebrates, and suggests that the early evolution of snakes occurred in aquatic environments. © 2004 The Linnean Society of London, Biological Journal of the Linnean Society, 2004, 81 , 469–482.