Doctor of Philosophy (PhD)
In a world of rapidly changing environmental conditions, species must effectively respond to their changing habitat or risk extinction. The goal of my dissertation is to elucidate the origins and mechanisms underlying the recent successful population expansion of the invasive coral Oculina patagonica in the Mediterranean Sea. To do this, I have utilized nuclear markers and next-generation sequencing data for the coral host and its algal symbiont as well as environmental data. Although only recently first described from the waters of the Mediterranean, genetic, historical demographic, and fossil evidence suggests that O. patagonica has not been anthropogenically introduced from the western North Atlantic. Instead, my results support the hypothesis that Oculina spp. has had a long history in the eastern Atlantic but remained undetected until it recently began expanding in the Mediterranean to invasive numbers, likely in response to environmental changes. Next, I found that the symbiotic algal communities harbored by Oculina corals vary geographically, and that this variation does not match the geographical variation of the host’s genetics. Instead, sea surface temperature is better correlated to symbiotic community, particularly in the Mediterranean, which may reflect acclimatization to local thermal conditions. Finally, in a closer inspection of a rapid poleward range expansion of O. patagonica along the Spanish Mediterranean coast, I found increased genetic diversity and adaptation to temperature that may have promoted its success. Together, my dissertation chapters shed light on the mechanisms that have allowed a coral to be successful despite stressful and changing environmental conditions. Unlike many previous studies aimed at assessing the adaptive capabilities and long-term success of tropical corals, my dissertation focusses on the success and adaptive potential of an understudied temperate coral. The findings presented here support the knowledge that O. patagonica is able to successfully respond to changing environmental conditions in its native range via both symbiont switching and host adaptation.
Document Availability at the Time of Submission
Release the entire work immediately for access worldwide.
Leydet, Karine Eliane Posbic, "Phylogeography of Oculina Corals and their Algal Symbionts: Insights into the Origin and Expansion of Oculina Patagonica in the Mediterranean" (2016). LSU Doctoral Dissertations. 537.