Award: OCE-1924498

Future increases in sea temperatures are expected to have far-reaching and detrimental consequences for marine organisms. Faced with challenging environmental conditions, organisms must either move to more favorable environments, acclimate to maintain homeostasis, or adapt through genomic changes to the new thermal regime, otherwise local extinction will occur. For marine benthic organisms (MBIs) that are largely sedentary, their capacity to migrate is dependent on larval dispersal. This dependency on larval dispersal for connectivity could have negative consequences under climate change as elevated temperatures are expected to reduce larval dispersal, potentially inhibiting species range shifts. The research team studied populations of four marine invertebrate species (coral, sea urchin, oyster, ascidian) across the substantial thermal gradient along the northeastern Arabian Peninsula as a natural system to quantify the effects of these regions with different temperatures on dispersal, genetic connectivity and adaptation. In this collaborative project with Dr. John Burt (New York University Abu Dhabi, United Arab Emirates), we used a multidisciplinary approach combining field work and laboratory experiments to determine the genetic relationships of individuals from four MBI species that are distributed the worlds warmest reefs in the Persian/Arabian Gulf (PAG). We completed field collections of all four species from multiple locations along the northeastern Arabian Peninsula. Using a combination of whole genome comparisons and reduced representation sequencing, the degree of population genetic structure varied between each species. We generated reference genomes for each species, including one of the most heterozygous marine species (the sea urchin Echinometra sp. EZ) reported to date. We observed significant though limited genetic subdivisions between locations for the sea urchin and oyster. For these species, populations from within the PAG were most different from those in the Gulf of Oman (GO). Genetic variation for the coral species showed higher population genetic structure between locations, but most of the differences were again between the two gulfs, with an intermediate location (Musandam) that showed the highest levels admixture. The ascidian species had the highest degree of genetic structure, likely due to the limited dispersal period of the larval stages, with significant genetic variation between geographically close locations. Genome scans to identify potential regions associated with adaptation to the extreme environment of the PAG resulted in identification of multiple genes that may confer a higher tolerance to warmer, high saline habitats. Moreover, due to the compact genome of the ascidian, we also identified multiple examples of variation in gene copy number for individuals in the PAG when compared to individuals in the GO. These insights resulting from this project have been productive in closing an important gap of knowledge for the population genetic relationships of marine species with geographic ranges encompassing broad differences in temperature and salinity. This project resulted in Broader Impacts related to research training, outreach to the community, and an international collaboration. Student-centered training was completed for two postdoctoral scholars as well as multiple graduate and undergraduate students throughout the life of the award. All trainees supported through this award led research in the field or the laboratory, presented at conferences, contributed to publications or led information activities for current and incoming undergraduate students majoring in STEM. Our research successes expanded opportunities for undergraduate students to engage in their first research experiences. The international collaboration with Dr. Burts lab resulted in unique training opportunities for the postdoctoral scholar as well as synergistic experiments combining field and laboratory experiments. Last Modified: 06/27/2024 Submitted by: AdamReitzel