Comparative phylogeography of three anuran species in the Eastern Cape Province forests, South Africa

Kushata, Judith Natsai Theodora (2018-12)

Thesis (MSc)--Stellenbosch University, 2018.


ENGLISH ABSTRACT: Taxa with different degrees of habitat specificity have been known to be susceptible to varying factors imparting fragmentation within forests. Therefore, delimiting their evolutionary history through population genetics is bound to shed light on the impact paleoclimatic and biogeographical events may have had in shaping their contemporary genetic structure. This study aimed at examining evolutionary relationships among populations of three anuran taxa; Anhydrophryne rattrayi, Arthroleptis wahlbergii and Cacosternum nanum within two indigenous forest types, the Afromontane forests and Indian Ocean coastal belt forests (IOCB) in South Africa. The former two species are leaf litter forest dependent and direct developing frog species whereas the former is a generalist species dependent on open water throughout its life stages. Phylogenetic reconstructions were inferred from combined mitochondrial DNA sequence data (16S rRNA and Cytochrome b) whereas only Cytochrome b data was analysed for phylogeographic analyses. Analyses of phylogenetic relationships within the two forest specialists (Anhydrophryne rattrayi and Arthroleptis wahlbergii) detected strongly supported clades with marked genetic variation and structure between populations, absence of shared maternal haplotypes indicating limited maternal gene flow between populations of these species. Lineage diversification within forest dwelling species followed the Plio-Pleistocene climatic perturbations indicating the influence of these paleoclimatic events as well as barriers in isolating populations to several refugia habitats. Contrarily, the generalist species, Cacosternum nanum revealed presence of low support and unresolved phylogenetic structure, connectivity between populations indicated by high maternal gene flow and the recovery of younger lineages suggesting that the species’ ecology may aid its dispersal abilities, subsequently, increasing its persistence, even during climatic stresses. Coupled with the different ecological mechanisms and life history traits of these taxa, populations may potentially be reproductively isolated and overtime, result in cladogenesis. This study thus suggests conservation management and decisions to be cognisant of the genetic uniqueness recovered using mtDNA of the forest specialist populations given the already fragmented habitats they occur in. Overall, this study lays grounds for several interesting biological questions such as possible taxonomical reclassification of the A. wahlbergii Mbotyi population and other statistical inferences made such as the inclusion of nuclear loci in the dataset.

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