[Coral-List] New manuscript comparing coral host and symbiont genetic structures

sarah davies daviessw at gmail.com
Thu Mar 10 10:11:47 EST 2016

Dear Listers,

We would like to draw your attention to our exciting new preprint posted on


Many reef-building corals acquire their algal symbionts (*Symbiodinium sp.*)
from the local environment upon recruitment. This horizontal transmission
strategy where hosts pair with locally available symbionts could serve to
increase coral fitness across diverse environments, as long as hosts
maintain high promiscuity and symbionts adapt locally. Here, we tested this
hypothesis in two coral species by comparing host and symbiont genetic
structures across different spatial scales in Micronesia. Each host species
associated with two genetically distinct *Symbiodinium* lineages,
confirming high promiscuity in broadly dispersing hosts. However, contrary
to our initial expectation, symbiont genetic structure was independent of
physical barriers to dispersal between islands, unlike genetic structure of
their hosts that was nearly perfectly explained by ocean currents. Instead,
*Symbiodinium* consistently demonstrated genetic divergence among local
reefs and between the two host species at each island, although not
necessarily between distant islands. These observations indicate that
*Symbiodinium* lineages disperse much more broadly than previously thought
and continuously adapt to specific hosts and reef environments across their
range, following the classical Baas Becking′s hypothesis: ″Everything is
everywhere, but the environment selects″. Overall, our findings confirm
that horizontal transmission could be a mechanism for broadly dispersing
coral species to enhance their local fitness by associating with locally
adapted symbionts. Dramatic differences in factors driving the genetic
structures of horizontally-transmitting corals and their *Symbiodinium*
imply that viewing their combined genomes as a single entity (′hologenome′)
would not be useful in the context of their evolution and adaptation.

Please feel free to make comments directly on Biorxiv or email me
personally (daviessw at gmail.com) with any questions or concerns.

We hope the list finds this paper of interest.


Sarah W. Davies on behalf of all coauthors

Sarah W. Davies M.Sc. Ph.D.
Postdoctoral Research Associate
Department of Marine Sciences
University of North Carolina at Chapel Hill
daviessw at gmail.com
Twitter: @DaviesswPhD

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