Species boundaries and conservation of the velvet worm genus Peripatopsis in South Africa
Thesis (MSc)--Stellenbosch University, 2016.
ENGLISH ABSTRACT: This study examined biogeographical and taxonomic relationships within the genus Peripatopsis with a special emphasis on the Peripatopsis capensis species complex using phylogenetic analyses, population genetics, divergence time estimation, ancestral area reconstruction, scanning electron microscopy, and gross morphological analysis. A total of 104 specimens were collected from 21 localities from the known distribution of the Peripatopsis capensis species complex in the Western Cape, while 54 specimens from prior studies on the Peripatopsis genus from the Western Cape, Eastern Cape, and KwaZulu-Natal were used for the analysis of the genus. Two partial gene fragments were selected for this study, namely the mitochondrial DNA cytochrome c oxidase one subunit (COI) and the 18S rRNA nuclear DNA gene locus. DNA sequences were analysed using phylogenetic methods and divergence time dating. The P. capensis species complex population genetic analyses were conducted on COI, while ancestral area inference for Peripatopsis was carried out using COI and 18S. For the P. capensis species complex geographic boundaries amongst cryptic lineages were inferred using Phylogeobuilder and evolutionary drivers of cladogenesis were determined for the latter as well as for the genus. A conservation assessment was carried out on described species using the IUCN red list framework and phylogenetic diversity indexes. Phylogenetic analysis reveals that P. capensis is a species complex comprised three geographically discrete and statistically well supported clades. Peripatopsis was retrieved as a genus comprising 12 statistically well supported and taxonomically described species, with three species being retrieved as non-monophyletic. Divergence time analysis results revealed Plio/Pleistocene diversification for the P. capensis species complex and an early Miocene diversification for the Peripatopsis genus coincident with climatic amelioration during the time period. The ancestor of the latter originated in the geomorphic province delineated as the Syntaxis Cape Fold Mountain region. While gross morphological characters for P. capensis such as leg pair number was invariant, scanning electron microscopy (SEM) yielded differentiating characters, albeit limited (e.g. dermal papillae and male genital pads). Two new Peripatopsis species are described in the present study. According to the IUCN framework all described species within the Peripatopsis genus require red listing and phylogenetic diversity indexes have highlighted the Cape Peninsula and the Central Cape Fold mountains as regions with a rich evolutionary history and high evolutionary potential.
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