Electronic Theses and Dissertations

Date of Award


Document Type


Degree Name

M.S. in Biological Science



First Advisor

Brice P. Noonan

Second Advisor

Rebecca Symula

Third Advisor

Ryan Garrick

Relational Format



Madagascar is an extremely diverse and geographically complex area boasting levels of endemism that blatantly raise questions about their origins. There is evidence that these endemics arose via insitu diversification during Madagascar's ~88 million year isolation, even though it was essentially in the middle of Gondwana with ample opportunity to acquire inhabitants. Madagascar's high levels of diversity and endemism make it an ideal location to study speciation, especially considering the evidence that such high levels speciation occurred in Madagascar itself. Several hypotheses have been formulated to relate the complex geography to genetic divergence, and thereby speciation. I explore three hypotheses concerning the effect of mountains, rivers, and watersheds on the genetic distribution of the endemic Malagasy ant species Odontomachus coquereli. I recovered three genetic clusters from STRUCTURE arranged from north to south. Genetic diversity in these clusters decreases southward, suggesting a southward migration. Divergence time analysis in IMa2 indicates that these clusters were formed by splits during the last two consecutive ice ages, and the geographical positioning of these clusters indicates that these splits coinciding with ice ages were aided by different montane refugia within the species. Together, the data show that climate change and refugia have been the driving force of genetic structuration in this species.

Included in

Biology Commons



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