Host identity and symbiotic association affects the genetic and taxonomic diversity of the clownfish-hosting sea anemone microbiome

All eukaryotic life engages in symbioses with a diverse community of
bacteria that are essential for performing basic life functions. In many
cases, eukaryotic organisms form additional symbioses with other
macroscopic eukaryotes. The tightly-linked physical interactions that
characterize many macroscopic symbioses creates opportunities for
microbial transfer, which likely affects the diversity and function of
individual microbiomes, and may ultimately lead to microbiome convergence
between distantly related taxa. Here, we sequence the microbiomes of five
species of clownfish-hosting sea anemones that co-occur on coral reefs in
the Maldives. We test the importance of evolutionary history, clownfish
symbiont association, and habitat on the genetic and predicted functional
diversity of the microbiome, and explore signals of microbiome convergence
in anemone taxa that have evolved symbioses with clownfishes
independently. Our data indicate that host identity shapes the majority of
the genetic diversity of the clownfish-hosting sea anemone microbiome, but
predicted functional microbial diversity analyses demonstrate a
convergence among host anemone microbiomes, which reflect increased
functional diversity over individuals that do not host clownfishes.
Further, we identify up-regulated microbial functions in host anemones
that are likely affected by clownfish presence. Taken together our study
reveals an even deeper metabolic coupling between clownfishes and their
host anemones, and what could be a previously unknown mutualistic benefit
to anemones that are symbiotic with clownfishes