High genetic similarity between geographically distant populations in a sea anemone with low dispersal capabilities

Samples of the large sublittoral sea anemoneUrticina eques(Gosse) were collected from three localities in the northern North Sea and from one locality in the northern Irish Sea. Around the coast the total distance between sampling sites is approximately 1,200 km. The species has a large lecithotrophic larva which may not be planktonic. All samples were screened genetically for 13 loci coding for 11 different enzymes. Results overall indicated a high degree of genetic uniformity over the four populations sampled (FST= 0·025). The data are discussed in relation to current ideas of larval dispersal and results from other similar studies. It is concluded that the lack of genetic differentiation shown byUrticina equesis surprising given the apparently poor dispersive powers of the larva.