Meeting Abstract
Interspecific hybridization plays an important role in adaptive evolution by increasing genomic diversity. Hybridization is common in marine invertebrates, including reef-building corals that externally fertilize gametes. In the Caribbean, hybridization occurs between Acropora palmata and Acropora cervicornis. Unlike the parental species, the hybrid can occupy non-parental niches, seems to be more thermotolerant and less susceptible to disease. While A. cervicornis and A. palmata populations continue to decline, recent field observations suggest that the relative abundance of hybrids has increased. However, it remains unclear if this increase in hybrid abundance is the result of asexual fragmentation of existing hybrids, ongoing generation of novel F1 hybids, hybrid mating, or a combination of these mechanisms. In this study, we used 13 microsatellite markers to identify ancestry of hybrids collected in Belize, Curacao, Bahamas and U.S. Virgin Islands. Of these field-identified hybrids, 19% were categorized as complex hybrids resulting from backcrossing of an F1 hybrid with either parental species or second generation hybrids. To better understand the ancestry of these hybrids, we deep-sequenced and assembled the genomes of A. cervicornis and A. palmata and shallow-sequenced 20 individuals for each species collected from across the species ranges to identify single nucleotide polymorphism (SNP) markers with fixed differences between species. The hybrids were screened using these SNPs and the resulting hybrid ancestry assessment was compared with the microsatellite results. The two novel acroporid genomes not only allow for studies of acroporid genome structure but also help resolve the historical reproduction patterns of the parental species and hybrids.
