The effects of asexual reproduction and inter-genotypic aggression on the genotypic structure of populations of the sea anemone Actinia tenebrosa.

Genotype frequencies of adult and juvenile Actinia tenebrosa from 2 populations showed that settlement and recruitment predominantly involved the localised asexual (ameiotic) proliferation of established genotypes. However, there is strong indirect evidence that the genotypic variation was generated by sexual reproduction. Genotypic structuring of these populations was detected at 2 levels. First, coarse clumping of genotypically identical adults and juveniles occurred on a scale consistent with the pattern of asexual dispersal. Second, fine-scale clustering of genotypically identical adults and juveniles occurred on a scale consistent with predicted effects of inter-genotypic aggression. Inter-genotypic aggression seems certain to play an important role in inter-genotypic competition for recruitment space and should reduce the input of genotypic variation into established populations. The applicability of the Strawberry-Coral Model to the life history of this species is discussed.