Abstract
If phenotypic plasticity is adaptive, then prior exposure to a stressor
should reduce effects arising from subsequent stressor exposure. Here,
we test the hypothesis that corals exhibit adaptive plasticity to a
stressor (vermetid gastropods) mediated by their extended phenotype
(coral-associated bacteria). We used a reciprocal transplant experiment
to evaluate corals that varied in their prior exposure to vermetid
gastropods, a known biotic stressor. We measured a suite of traits
associated with coral performance, many of which showed a plastic
response to vermetid exposure: decreased calcification, increased
microbial diversity, and shifted microbial composition. Most traits
(e.g., tissue thickness) also showed a signature of previous exposure
environment that persisted after exposure reversal. These phenotypic
differences are likely genetic, as reefs with and without vermetids
largely comprised of two mitotypes. We suggest cryptic coral variation
contributes to different community trajectories, with thin-tissue types
more prone to disturbance and subsequent colonization by other species.