Snake-eyed skinks are relatively small lizards of the genera Panaspis and Afroablepharus. Along with closely-related scincid taxa, the allocation of these genera has been constantly rearranged based on morphology, ecology and biogeography. Members of these genera occur primarily…
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One of the fundamental questions in biology is the origin of species. Considerable insights into the processes that drive speciation have come from ancient lake systems. In this thesis, I present insights into speciation processes by investigating the species radiations of the a…
Laboratory experiments were designed to identify distinct biological attributes that might separate and help clarify the taxonomic status of one indigenous and six exotic populations of Diaeretiella rapae (M'Intosh). Experiments were conducted to investigate courtship and mating…
Oceanographic features such as currents, fronts and upwelling cells have been recognised as possible factors driving population differentiation within species. The Benguela Current is one of the oldest upwelling systems in the world, located off the west coast of Southern Africa…
This thesis explores the far-reaching impacts of sexual conflict over care on a suite of traits in the penduline tit family (Remizidae), further confirming the intricate relationships between parental care, mating systems and sexual selection. The results reveal the first geneti…
The evolution of isolating mechanisms within a species population impedes gene flow. This allows isolated populations to diverge along different trajectories, which may ultimately lead to the formation of new species. Our attempts to understand the evolution of isolating barrier…
This study is primarily concerned with assessing the influence of the sex determination genes, transformer (tra), doublesex (dsx) and fruitless (fru) on three sexually dimorphic traits within Drosophila; pheromone blend, courtship song and sex comb tooth number. The sex determin…
Drosophila ananassae inhabits most of the tropical and subtropical regions of the world. In contrast to D. melanogaster and D. simulans , populations of D. ananassae exhibit a distinct genetic population substructure through most of their geographic range. Studies of D. ananassa…
The prevalence of invasive species poses a major threat to natural and agricultural systems worldwide. Biological control can be an effective means of managing pests while minimizing the use of pesticides, but the method suffers from unpredictability. The success rate of biologi…
I conducted a morphological field study of two primate populations ( Macaca ochreata ochreata and M. o. brunnescens of Sulawesi, Indonesia) that have been isolated from one another for approximately 9,000 years, under subtly different ecological conditions. My aims were to (1) d…
Hybridization has traditionally been viewed as a happenstance that negatively impacts populations, but is now recognized as an important evolutionary mechanism that can substantially impact the evolutionary trajectories of gene pools, influence adaptive capacity, and contravene …
Evolutionary history is typically portrayed as a branching phylogenetic tree, yet not all evolution proceeds in a purely bifurcating manner. Introgressive hybridization is one process that results in reticulate evolution. At ancient time scales, lateral movement of genetic mater…
Closely related taxa frequently exist in sympatry before the evolution of robust reproductive barriers, which can lead to substantial gene flow. Post-divergence gene flow can promote several disparate trajectories of divergence ranging from the collapse of the taxa to the streng…
This dissertation investigates patterns of sex chromosome evolution in the dioecious plant Rumex hastatulus, an annual species with two distinct largely allopatric sex chromosome cytotypes (females XX and males XY or XYY). My thesis addresses three general observations often ass…