[Coral-List] [Cnidarian-dinoflagellate-symbiosis] genetic connectivity of Symbiodinium individuals within a single colony

[Mikhail Matz]

you got it, Thomas. No, corals cannot switch symbionts for a new strain as adults. Think of symbionts as efficient parasites that never give up their host. Yes, symbionts can infect only the new generation of corals, so, from popgen point of view, coral generations = symbionts generations.

Misha Matz

> On Mar 21, 2019, at 5:34 AM, Thomas Krueger <thomas.krueger at epfl.ch> wrote:
> 
> Here is a curious question: If the symbiont community in a coral host, as some publications suggest, consists of a single genet (i.e. genetically identical individuals aka clones), how can bleaching ever act as a positive selective force and reshape the surviving residual population towards a more heat resistant one? It literally would require uptake of genetically different individuals (of the same species) from the water column to diversify the genetic pool. Has someone used sequencing data to look at whether it is the residual population that recolonizes a bleached coral or whether it receives new settlers from the water column? If a single genet of Symbiodinium in colonies is really a dominating feature and if it does not change through bleaching events, then horizontal transmission might not really be such a big thing and there is little exchange with environmental Symbiodinium populations in the adult stage (exchange maybe, but not to the point that it reshapes colonies to the point that we can detect an altered genetic pool of the dominating species). This in turn would mean that the coral's larval and juvenile stage is the crucial stage that shapes the holobiont assemblage for the symbiont side. Any thoughts?
> 
>  
> 
> _______________________________________________
> Cnidarian-dinoflagellate-symbiosis mailing list
> Cnidarian-dinoflagellate-symbiosis at auburn.edu
> http://listserv3.auburn.edu/mailman/listinfo/cnidarian-dinoflagellate-symbiosis