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African Zoology

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Are melanistic populations of the Karoo girdled lizard, Karusasaurus polyzonus, relics or ecotypes? A molecular investigation

Hanlie M. Engelbrecht, P. le Fras N. Mouton, Savel R. Daniels

Abstract


It has been proposed that melanism in cordylids evolved in response to a single climatic event and that melanistic populations of Karusasaurus polyzonus are relictual. This study investigates the genetic relationships of melanistic and non-melanistic populations of K. polyzonus along the west coast of South Africa. Thirty-five specimens of K. polyzonus were collected from three ‘melanistic’ and eight ‘non-melanistic’ sample localities. Partial sequence data were derived for two mitochondrial DNA loci (16S rRNA and nicotinamide adenine dinucleotide  dehydrogenase component 2 (ND2)) and analysed using maximum parsimony, maximum likelihood and Bayesian inference. In addition, a haplotype network was constructed using TCS and an analysis of molecular variance (AMOVA) was  conducted. The derived topologies were highly congruent and showed that melanistic and non-melanistic populations were interdigitated on all tree topologies and a number of haplotypes were shared between melanistic and non-melanistic specimens. These results suggest that melanistic populations of K. polyzonus are ecotypes, not relics.


Key words Karusasaurus polyzonus, coastal climatic conditions, melanism, 16S rRNA, ND2.




http://dx.doi.org/10.3377/004.046.0105
AJOL African Journals Online