Meeting Abstract
Morphological plasticity is a genotype-by-environment interaction that enables organisms to increase fitness across varying environments. When faced environmental heterogeneity, an animal holobiont may acclimate by shifting the composition of the associated bacterial community. By inducing morphological plasticity in three confamilial sea urchins, we test the hypothesis that the bacterial community co-varies with the expression and magnitude of plasticity. While each urchin has a species-specific bacterial community, the expression of plasticity resulted in the convergence on a phenotype-specific bacterial community, with community shifts being proportional to the expression of the trait. Moreover, associating with a phenotype-specific bacterial community was independent of ecological drift, diet quality, and developmental stage, even though the bacterial communities established by the eggs change gradually during embryonic and larval development. Animal-associated bacterial communities are also taxonomically distinct across host biogeography. Using larvae of the echinoid Strongylocentrotus droebachiensis from coastal locations in the Pacific and Atlantic Oceans, we test the hypothesis that host geographical origin better correlates with community composition than does local variation (e.g., diet and phenotype). Our comparisons of the bacterial communities associated with S. droebachiensis larvae suggest that geographic location better correlates with community composition than local biological (e.g., phenotype) and ecological (e.g., diet quantity) variation. Taken together, these results suggest that echinoid larvae associate with a phenotype-specific microbial community that is specific to but can be masked ecologically by host biogeography, implying that scaling and the potential for ecological masking should be considered when studying host-microbiome dynamics across an ecological landscape.
