Abstract
Dispersal patterns within species have profound consequences for population dynamics and species’ evolutionary trajectories. Intraspecific interactions and habitat variability dictate dispersal trends. Given the rate at which habitat is altered globally by climatic and anthropogenic influences, it is important to understand historic dispersal trends to assess the impact these changes may have on biodiversity. Madagascar is of particular interest as it harbours unique biodiversity. The lemurs on Madagascar represent a distinct radiation of primates and make up 21% of the species in this order. Yet, the processes that have led to current species distributions across Madagascar remain unresolved.
Aye-ayes have the widest geographic distribution of all lemurs and are found across multiple forest types on the island. However, their cryptic nature makes them especially elusive and therefore relatively little is known about their evolutionary history. I make use of innovations in the field of molecular genomics to sample genomic regions of this species to elucidate historic gene flow among populations.
I developed a novel method of sampling mitochondrial DNA from aye-ayes’ distinct feeding traces to sample from two sites in south-east and west of Madagascar towards the extents of the aye-aye’s geographic distribution. These data supplemented sampling by Madagascar Biodiversity Partnership to provide the most geographically extensive genomic sampling of this species to date. I obtained genomic DNA to investigate the role of biogeographic processes and sex-biased dispersal in aye-ayes’ population genomic structure.
I used different genomic markers to assess diversity and to resolve mechanisms that have led to aye-aye population genomic structure. I revealed matrilineal structure on the maternally inherited markers, whereas male-specific Y-chromosome marker systems showed weak structure, indicating male-mediated gene flow. Analysis of diversity in a phylogeographic context indicated that geographic distance drives genomic structure, yet I show some support for two biogeographic hypotheses which suggest that changes to riparian vegetation during the Pleistocene may have impacted connectivity among aye-aye populations.
I provide interesting avenues for future research to better understand lemur biogeography and social organization, and findings can be integrated into conservation planning, particularly initiatives with focus on protecting genomic diversity in this species.
