Selection for asexual reproduction in an Antarctic polychaete worm

Abstract

The Antarctic oweniid polychaete Myriochele cf. been' frequently reproduced asexually by binary fission. The frequency of asexual reproduction was related to size-selective mortality and was highest (nearly 30 % of the population) in a constant physical environment where the important potential selective forces are biological. Asexual individuals were abundant in a dense assemblage of Antarctic infauna. Individuals produced by fission had a size refuge from all important sources of mortality, especially crustacean predators that kill the larvae and juveniles of other soft-bodied infauna. Asexual reproduction was rare in Antarctic habitats where larval invasion was more likely and there was little refuge in size from various sources of adult mortality. No asexual reproduction was observed in an Alaskan species, M. oculata, living in habitats that were frequently disturbed by physical and biological process.