9707568 Lamb Biogeography addresses the influence of earth history on the diversification of life. Isolation plays a key inceptive role in this diversification: groups of organisms separated geographically from others assume their own phylogenetic and biological trajectory. One potential effect of long-term geographic isolation is the divergence (origin) of unique species that are restricted or endemic to an isolated area (e.g., marsupials in Australia). In this research, Lamb and Bauer will examine the role that geologic and climatic events have played in shaping the extensive regional endemism observed among lizards in southern Africa. To assess the influence of regional events on lizard diversity, they will utilize more than 2,000 base pairs of DNA sequence (sampled from three mitochondrial genes) and a suite of morphological characters to construct a genealogical or phylogenetic tree (topology) for each of five different lizard genera. The five different topologies will then be compared for similarities (congruence) in overall shape in order to identify common patterns and biogeographic factors. Hypotheses that divergence of these lizard taxa are linked to geotectonic episodes and paleoclimatic shifts in the early Miocene and Plio-Pleistocene periods will be tested. The research also will provide phylogenetic and classification information for several taxa that are poorly known. Finally, there is substantive involvement of undergraduate students in almost every phase of the project.
