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

Our studies of sea anemones reveal that asexual reproductioncan lead to the amplification of particularly successful genotypesPopulations of Haliplanella luciae studied to date are characterizedbv exclusively asexual reproduction and typically are dominatedby one or a few clones A field translocation experiment suggeststhat this population structure may result from differentialmortality among colonizing clones most of which are not preadaptedto local conditions Asexual reproduction by survivors leadsto extensive multiplication of one or a few genotypes Metridiumsenile reproduces sexually and asexually and we ofler evidencethat there is significantly less vegetative proliferation butlarger individual body size in areas of low tidal current velocitythan in areas of moderate to high velocities This may indicatethat small individuals (produced asexually) are at a particularfeeding disadvantage in slowly moving water leading to an emphasison maintaining individual body sizeat the expenseol asexualleproduction Individuals heterozygous fora phosphoglucose isomerase(PG1) locus appear to be more successful than homozygotes inmaximizing body size independent of current regime and in maintaininglarge clone biomass in low velocity habitat Members of heterozygoteclones are significantly more dispeised some clonemates beingseparated by 9 meters or more and are overrepresented in thelow velocity habitat Selection against (small) homozygotes activechoice of habitat, and passive differential dispersal of larvaeand adult anemones may all contribute to this pattern.