Patterns of Introgression in Acroporid Genomes
The sympatric corals Acropora palmata and A. cervicornis form the hybrid, A. prolifera, whose abundance has continued to increase, either through fragmentation or sexual reproduction, while the parental species decline. Previous work indicates that weakened prezygotic isolation mechanisms in A. cervicornis but not A. palmata could allow for continuous unidirectional gene flow between the two species. Furthermore, evidence for asymmetric introgression from A. palmata to A. cervicornis has been recorded previously.
We are using genomic sequence data (See Omic Resources) from the two parental species and their hybrids to further characterize the patterns of genomic synteny, divergence and introgression across hybrid zones.
We identified genetic variants between the parental species (Kitchen et al., bioRxiv pre-print) that will allow us to understand introgression in the hybrids and has already led to the development of the STAG database.
The hybrid larvae do not acquire their symbionts from their parents, and must take them up from the environment. We want to explore the preference of hybrids to parental symbiont "strains", whether they choose the A. palmata- or A. cervicornis-like symbionts. Penn State graduate student Hannah Reich is looking for strain-specific markers using the draft Symbiodinium fitti genome in a similar manner to how we identified the species-specific coral markers. These markers will allow us to genotype the symbionts and assess the genetic background of hybrid-symbiont associations.