Meeting Abstract
Adult organisms may “prime” their offspring for environmental change through a number of genetic and non-genetic mechanisms, termed parental effects. Some coral species can alter their thermal tolerance by shuffling proportions of their symbiont communities, but it is unclear if this plasticity can prime larval offspring in corals exhibiting maternal symbiont transmission. We evaluated symbiont community composition in tagged Montipora digitata from Orpheus Island, AUS, over two successive annual spawning seasons, the second of which overlapped with the 2016 mass coral bleaching event on the Great Barrier Reef. We applied amplicon sequencing of the ITS2 locus in four families (adult colonies and ten eggs per family) to characterize the potential for symbiont shuffling and to determine whether or not shuffled abundances are preserved in gametes. Symbiont cell densities and photochemical efficiencies of the symboints’ photosystem II differed significantly among adults in 2016, suggesting differential responses to increased temperatures. The dominant symbiont haplotype, a representative of clade C15, was not significantly different among families or over time. However, low-abundance (“background”) ITS2 types differed more among years (2015 vs. 2016) than between life stages (parent vs. offspring), suggesting that background shuffling can occur and that these symbiont community changes are heritable. Although more work is needed to establish the role of background symbionts in holobiont thermal tolerance, this is the first evidence of shuffling extending to early life-history stages and provides evidence that plastic changes in microbial communities may serve as a mechanism of coral acclimation to changing environmental conditions.
