Complex patterns of speciation and diversity among African frogs (genus Phrynobatrachus)

Phylogenetic studies have identified numerous vertebrate groups endemic to sub-Saharan African, revealing that continental endemism is associated with substantial morphological diversity. The puddle frog Glade is one of the most speciose Afrotropical anuran lineages, comprising more than 75 species. The heterogeneity of this group is reflected in its wide habitat and altitudinal range, tremendous variation in adult body size, alternative reproductive modes, including species with terrestrial eggs and terrestrial larvae, and extreme karyotypic diversity in comparison to other closely related frogs. The goal of this thesis is to document and elucidate patterns of speciation and diversity among puddle frogs (Anura: Phrynobatrachidae), and to determine what factors contributed to their successful radiation across sub-Saharan Africa. Phylogenetic relationships among puddle frogs are estimated based on analyses of mitochondrial and nuclear DNA using separate and combined partitions under maximum parsimony, maximum likelihood, and Bayesian criteria. The monophyly of the Phrynobatrachidae is well supported; three major clades of Phrynobatrachus are identified. Bayesian molecular dating indicates puddle frogs originated in the Cretaceous with interspecific diversification taking place throughout the Cenozoic. The vast majority of species are distributed within one of five geographic zones; the fewest occur in southern Africa. The complex biogeographic history of the two most speciose puddle frog clades includes origination within one zone, invasion into other regions, and subsequent recolonization of the zone of origin. The majority of species favor forest over savannah habitats, and three major clades of highland species are identified. Each major Glade follows an evolutionary trend of body size reduction with both extent of pedal webbing and carpal configuration associated with body size evolution. Changes to phalangeal morphology are most commonly observed in miniaturized species and include asymmetric loss or duplication of phalanges in both the forelimb and hind limb. Alternative reproductive modes occur within both miniaturized and non-miniaturized species; Phrynobatrachus independently evolved alternative reproductive modes at least seven times, including terrestrial deposition of eggs and terrestrial, non-feeding larvae. Lastly, karyotype data suggest chromosomal evolution also contributed to the successful diversification of this widespread lineage across sub-Saharan Africa.