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Standing genetic variation is a major driver of fitness and resilience, and therefore of fundamental importance for threatened species such as stony corals. We analyzed RNA- seq data generated from 132Montipora capitataand 119Pocillopora acutacoral colonies collected from Kāneʻohe Bay, Oʻahu, Hawaiʻi. Our goals were to determine the extent of colony genetic variation and to study reproductive strategies in these two sympatric species. Surprisingly, we found that 63% of theP. acutacolonies were triploid, with putative independent origins of the different triploid clades. These corals have spread primarilyviaasexual reproduction and are descended from a small number of genotypes, whose diploid ancestor invaded the bay. In contrast, allM. capitatacolonies are diploid, outbreeding, with almost all colonies genetically distinct. Only two cases of asexual reproduction, likelyviafragmentation, were identified in this species. We report two distinct strategies in sympatric coral species that inhabit the largest sheltered body of water in the main Hawaiian Islands. These data highlight divergence in reproductive behavior and genome biology, both of which contribute to coral resilience and persistence.Significance StatementGiven the threat posed to coral reef ecosystems by human caused climate change, there is a growing focus on developing strategies for the protection and restoration of these critical marine habitats. These efforts are however limited by our understanding of the diversity of coral survival and reproductive strategies. Our analysis of data from two coral species inhabiting the same Hawaiian bay found that one is a strict sexual outbreeder, whereas the other reproduces predominantly asexually (i.e., clonally) and includes both diploids and triploids. These results broaden our understanding of coral biology, adaptability, and evolution, and underpin future research into the mechanisms of coral resilience that can inform restoration activities. |
