OH THE PLACES YOUʻLL GO: POPULATION GENETICS AND PHYLOGEOGRAPHIC INSIGHTS IN WIDELY DISTRIBUTED MARINE TAXA

Abstract

Coral reef environments are some of the most diverse and productive ecosystems on this planet, providing cultural, economic, and ecological value. Although highly diverse, coral reefs have been impacted by anthropogenic stressors on a global scale and are among the most vulnerable habitats to future climate change. Due to anthropogenic impacts, coral reefs are experiencing phase shifts where an abrupt transition from one state to another due to a disturbance are happening more frequently. These phase shifts are not limited to coral-algal changes and reports and outbreaks from coral dominance to other marine invertebrate taxa are becoming more common. Most studies focus their efforts on species that are sensitive to anthropogenic impacts and climate change. Here I focus on some taxa, specifically the zoantharian genus Palythoa and the shrimp genus Stenopus, that are known to proliferate in anthropogenic disturbed habitats. The aims of this dissertation are to examine patterns of genetic structure to gain a better understanding of connectivity and phylogeography among species that tend to flourish in anthropogenic disturbed habitats. I wanted to access if generalist species that tend to do well and are expected to increase abundance and distribution under anthropogenic impacts and climate change show similar or different patterns of phylogeographic and population structure as those species that are declining from these same impacts. Using a single mitochondrial locus, I found cryptic lineages of Stenopus hispidus with one that was restricted to the Atlantic and another restricted to the Red Sea, Indian, and Pacific Oceans. For comparison, I selected a broadly distributed zoantharian, Palythoa tuberculosa, that is capable of rapidly increasing in abundance to monopolize large areas that are impacted by anthropogenic disturbance. Using nucleotide polymorphisms in a phylogenomic approach, I found cryptic diversity in this species. Finally, I focused in on a single monophyletic lineage of P. tuberculosa to examine population genetic structure using thousands of SNPs generated from ezRAD data, and infer population connectivity in P. tuberculosa across most sites in the Northwestern Hawaiian Islands and population structure among locations in the Main Hawaiian Islands. Rather than focusing on only those species declining in the face of climate change, I wanted to bring some attention and insight into species that are “winners” and might be expected to thrive in the face of climate change.