DNA PROFILING AND POPULATION HISTORY IN CONSERVATION

Abstract

The fundamental objective ofconservation genetics is the identification ofthe basic units of conservation. Central to this objective is the reconstruction ofthe adaptive and evolutionary history of populations to evaluate their conservation status. Evolutionary history involves both microevolutionary and macroevolutionary processes and adaptive history is the evolution ofspecific characters to selective ecological processes in differential heterogeneous environments. Neutral DNA markers such as mitochondrial DNA, minisatellites and microsatellites are most often used for reconstructing history and identifying conservation units. This thesis examined three biological systems: 1) an African cichlid, 2) Canadian moose populations and 3) eastern North American wolves and coyotes to test two hypotheses. Firstly, neutral DNA markers can be used to accurately reconstruct the evolutionary history ofpopulations. Secondly, neutral DNA markers are concordant with adaptive distinctiveness in reconstructing the adaptive history ofpopulations. Few studies have examined these relationships. Lake Magadi tilapia showed discordant patterns between adaptive morphological, physiological and behavioural characters and genetic structure assessed with mitochondrial DNA. I propose this discordance has resulted from selection acting on mitochondrial DNA that has often been assumed to be “neutral”. Neutral DNA markers accurately reflected the known history ofthe moose populations but discordant patterns were observed between neutral and functional loci indicating the former may not accurately reflect adaptive variation. DNA profiles of eastern wolves and coyotes showed a significant conflict in the interpretation ofmtDNA and microsatellite data compared to previous genetic studies that examined wolftaxonomy. The data were consistent with the hypothesis of a North American-evolved wolf. Coyote-like mtDNA was not of coyote origin but represented divergent but related sequences of a North American wolflineage independent of the gray wolf(C. lupus). Under this new model of eastern wolfevolution, we also identified the hybrid origin of eastern coyotes, contrary to previous interpretations, and genetically characterised different wolf “types” within Ontario. These findings could not reject the first hypothesis as neutral markers were used to reconstructthe histories ofthe three biological systems. However, the findings identified that it is important to ensure the neutrality ofDNA markers and thatsamples are representative ofthe taxa under investigation. The findings in this thesis did not support the second hypothesis, as neutral DNA markers were not concordant with adaptive characters, i.e. morphology, physiology and functional genetic markers.