THE PREDOMINANCE OF CLONES IN POPULATIONS OF THE SEA ANEMONE<i>ANTHOPLEURA ASIATICA</i>(UCHIDA)

Abstract

To assess the population structure of the sea anemone Anthopleura asiatica, sex ratios and acrorhagial responses were examined among ten populations in the Seto Inland Sea of Japan. In spite of the fact that all specimens were capable of eliciting an acrorhagial response on contact with other individuals of the same species, no response was found in certain populations. These populations were always composed of individuals of the same sex. This result indicates that examination of the response was effective in distinguishing clones of the anemone. On the basis of sex and acrorhagial response, each of the populations seems to consist of a single or a few clones, and moreover, one clone appears to be distributed over 5 km through six separate locations. Diversity of clones among locations may imply sexual recruitment in the past. The anemones probably prosper asexually in local populations while dispersal to new habitats is facilitated by sexual reproduction. The causes of the clones' predominance and the applicability of the Strawberry-Coral Model to the anemone are discussed.