Adaptive radiation in cordyliform lizards: An overview

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Abstract
MOUTON, P. LE F.N., and J. H. VAN WYK. 1997. Adaptive radiation in cordyliform lizards: An overview. Afr. J. Herpetol. 46(2): 78–88. Ecophysiological and behavioral character evolution in the Cordyliformes is discussed. Arguments are based on Lang's generic-level phylogenetic tree for the Cordyliformes, but with Platysaurus taken as the most basal genus in the Cordylidae. Ancestral values for reproductive mode, foraging mode, prey chemical discrimination ability and preferred substrate are evaluated using parsimony criteria and the Scincidae and Lacertoidea as outgroups. The available data suggest that, within Cordyliformes, sit-and-wait foraging, lack of prey chemical discrimination, and a rupicolous lifestyle co-evolved in the immediate ancestor of the Cordylidae, while viviparity evolved in the immediate ancestor of the Cordylus-Chamaesaura-Pseudocordylus clade. The highland distribution and viviparous reproductive mode of the latter clade suggest that the ancestor became adapted to cool regimes, in other words that the clade had a cold origin. The adaptive significance of the transitions to a sit-and-wait foraging mode, lack of prey chemical discrimination ability, and a rupicolous lifestyle in the ancestor of the Cordylidae remains unknown, but these transitions could have served as preadaptations which facilitated the invasion of highland areas by the Cordylus-Chamacsaura-Pseudocordylus clade. The distribution of extant species suggests that the Cordylidae/Gerrhosauridae divergence occurred in southern Africa, the former diversifying in the extreme southern regions of the subcontinent and the latter in the south-central regions. The rupicolous lifestyle and resultant low vagility of early cordylids probably prevented the family from reaching Madagascar before its separation from Africa.