Patterns and processes of adaptation in Lacertid lizards to environments in southern Africa

[摘要] ENGLISH ABSTRACT: The phenotype of an individual has often been used as the descriminating factor in distinguishingspecies. However, with the advent of more precise molecular techniques, the genotype of species isincreasingly being used as the preferred method in taxonomic classifications. Many taxa have recentlybeen demonstrated to be incongruent in terms of their genetic and morphological groupings, and thismay due to the influence that the environment may have on the morphological and functional aspects ofa species. Selective pressures often act upon the performance of a species within a particular habitatfirst, and then selection for the morphological characters that allow for optimal performance occurs.Should genetically disparate species inhabit a particular environment, convergence in morphologies andperformance may evolve. Historically, lizard species descriptions were based primarily on externalmorphologies, and thus misclassfication of species may have occurred due to mistakenly groupingspecies with convergent morphologies together. In the current dissertation, the links betweenmorphology, performance capacities, diet and behaviour is explored in comparison to the environmentand genetic relationships of southern African lacertid lizards. The performance capacities and associatedmorphological traits were expected to be more closely linked with the environment, and not closelylinked with genetic relationships. To investigate these expectations, a multidisciplinary approach wastaken, and genetic, morphological and performance analyses were done and compared with dietarybehavioural and environmental analyses. In the first chapter, the link between habitat openness and thelizard bauplans is investigated and the presence of convergent morphologies within this group of lizardsis uncovered. These convergences are shown to have resulted in misclassification of two lacertid species,and taxonomic revisions within the family are discussed. The second chapter explores the link betweenperformance and associated morphological traits, and the dietary composition of the members of theNucras genus. The third chapter identifies the link between the predator escape strategies employed bythe members of the Meroles genus, and their morphologies and performance capacities. The fourthchapter explores the intraspecific, inter-population differences in morphologies and investigates the linkbetween the morphological groupings and the population genetic groupings within Pedioplanislineoocellata. The final chapter identifies whether adaptation to a novel habitat can occur over arelatively short period of time, and the morphological traits, functional aspects, and population geneticstructure is investigated in conjunction with environmental analyses of vegetation and substrate betweenthe populations of Meroles knoxii. It was concluded that the morphological and functional aspects of thesouthern African lacertid lizards are more closely related to the environment, particularly themicrohabitat structure, than to their genetic relationships, and that future work using this group of lizardsshould involve a multidisplinary approach as different selective pressures are playing a role in shapingthe morphologies and performance capacities of these lizards, compared to those that are acting uponthe genotypes of the lizards.

[发布机构] Stellenbosch University