BAUER, A.M.; Villanova University: Phylogenetics and the Evolutionary Morphology of African Lizards

Hypotheses of relationship were erected for selected southern African lizard taxa on the basis of morphological and DNA (mitochondrial and nuclear) sequence data. The five independent lineages selected: the Pachydactylus group (Gekkonidae), Meroles (Lacertidae), Typhlosaurus and Scelotes (Scincidae), and the Gerrhosauridae, each exhibit significant variation in locomotor morphology that may be interpreted in light of the phylogenies generated. The most divergent locomotor morphologies in each lineage have evolved in association with sandy substrates, chiefly in the Namib Desert, and represent relatively recent adaptations to psammophily. The burrowing members of the genus Pachydactylus, once considered to form a natural group, are demonstrated to represent several distinct lineages. In one instance burrowing specializations are achieved as a result of paedomorphosis, while in another they are an outcome of the hypertrophy of digital structures. The Pachydactylus group of geckos includes approximately 70 species and serves as a particularly good system to ask a diversity of questions about the evolution of form and function. Much of the diversity of this group of geckos may be attributed to their high degree of substrate specificity and associated tendency to undergo lineage splitting as a result of habitat fragmentation over geological time.