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

Thomas Krueger thomas.krueger at epfl.ch
Thu Mar 21 10:34:27 UTC 2019


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?



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