| Summary: | Thesis (MSc)--Stellenbosch University, 2013. === ENGLISH ABSTRACT: In the present study I examined the phylogeography of the rupicolous Cape
girdled lizard, Cordylus cordylus. Samples were collected across the species
distribution range from 63 localities in the Eastern and Western Cape and Free State
provinces of South Africa, yielding a total sample size of 207 specimens. Four DNA
loci, two nuclear (PRLR, PTPN12) and two mitochondrial (16S rRNA, ND2), were
sequenced. Bayesian inference, maximum likelihood and maximum parsimony
methods were employed to test evolutionary relationships among populations,
followed by population structure analyses, divergence time estimations and niche
modelling. My results confirm the species monophyly and revealed the presence of
two distinct clades. Clade 1 comprised specimens from the western and southern
portions of the Western Cape coast, while clade 2 comprised specimens from the
southern and eastern Cape coast and adjacent interior of the Eastern and Western
Cape and Free State provinces. An area of sympatry between the two clades was
observed in the Breede river valley. The divergence time estimates revealed an
Early Pliocene (4.31 Ma), Late Miocene (6.01 Ma) divergence for each of the two
clades retrieved. Phylogeographic data suggest that clade 1 is younger (lower
haplotypic and nucleotide diversity), in comparison to clade 2. Furthermore, the
niche modelling shows that C. cordylus occupies a wide range of unfavourable
habitats. The absence of marked phylogeographic patterning within clades is very
uncharacteristic for a rupicolous vertebrate species. The ecological pliability and
generalist nature of C. cordylus presumably contributed to the observed
phylogeographic pattern and have facilitated the absence of within clade differentiation. Moreover, I suggest that microclimatic variables, rather than
geographic barriers influence the genetic structuring of C. cordylus.
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