Electronic Theses and Dissertations (PhDs)

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Browsing Electronic Theses and Dissertations (PhDs) by Keyword "Barking geckos"

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    Unravelling the speciation process in barking geckos (Ptenopus: Gekkonidae)
    (University of the Witwatersrand, Johannesburg, 2024) Becker, Francois S.; Tolley, Krystal A.; Graham J. Alexander
    Barking geckos (genus Ptenopus) are a group of terrestrial, burrowing lizards endemic to southern Africa, with three currently recognised species: P. kochi, P. carpi, and P. garrulus, the last containing the subspecies P. g. garrulus and P. g. maculatus. Males produce uniquely loud vocalisations to attract females to the burrows, a trait which is involved in mate recognition. I produced the first comprehensive phylogeny for the genus, which supported several deep divergences and the presence of unrecognised species. I then applied the unified species concept in an integrated taxonomic framework to delimit species within Ptenopus. I used multiple lines of evidence including genetic-spatial analyses, advertisement calls, ecological divergence, and morphology to test the evolutionary independence of putative species suggested by phylogenetic species delimitation analyses. Based on these findings, I suggest there is a total of eight species of Ptenopus, and that the two subspecies P. g. garrulus and P. g. maculatus should be elevated to full species. I provide provisional descriptions of four additional species. The advertisement calls and preferred habitats were clearly distinct among these proposed species, while morphological characters were generally less reliable for species identification. I also tested various candidate hypotheses of divergence drivers in the genus using multiple regression on matrix models (MRMs). The MRMs supported the hypothesis that substrate specialisation was the main factor over other factors as the key driver of divergence. Geographic barriers, including rivers and mountains or ridges, also appear to be important drivers of some of the more the recent divergences. The Namib Desert is the centre of diversity for the genus Ptenopus, containing seven of the eight proposed species. There was also strong evidence for reproductive character displacement in the advertisement calls of sympatric species, indicating the importance of calls in mate recognition and the maintenance of species boundaries. This is the first study to show evidence for reproductive character displacement of vocal traits in a non-avian reptile.