Asexual Reproduction, Population Structure, and Genotype-Environment Interactions in Sea Anemones

Abstract

Our studies of sea anemones reveal that asexual reproduction can lead to the amplification of particularly successful genotypes Populations of Haliplanella luciae studied to date are characterized bv exclusively asexual reproduction and typically are dominated by one or a few clones A field translocation experiment suggests that this population structure may result from differential mortality among colonizing clones most of which are not preadapted to local conditions Asexual reproduction by survivors leads to extensive multiplication of one or a few genotypes Metridium senile reproduces sexually and asexually and we ofler evidence that there is significantly less vegetative proliferation but larger individual body size in areas of low tidal current velocity than in areas of moderate to high velocities This may indicate that small individuals (produced asexually) are at a particular feeding disadvantage in slowly moving water leading to an emphasis on maintaining individual body sizeat the expenseol asexual leproduction Individuals heterozygous fora phosphoglucose isomerase (PG1) locus appear to be more successful than homozygotes in maximizing body size independent of current regime and in maintaining large clone biomass in low velocity habitat Members of heterozygote clones are significantly more dispeised some clonemates being separated by 9 meters or more and are overrepresented in the low velocity habitat Selection against (small) homozygotes active choice of habitat, and passive differential dispersal of larvae and adult anemones may all contribute to this pattern.