Morphological and other evidence on the degree of genetic differentiation between populations of Nereis diversicolor

Abstract

The pattern of paragnaths in Nereis diversicolor differs markedly between 17 populations from eastern and south-west England. There is a substantial heritable component to these differences, and there is no evidence that sediment type during development has any influence on them. Comparisons with previous studies reveal no consistent relationships of paragnath pattern with either sediment type or salinity. Evidence from scanning electron micrographs and correlations between different groups indicates that the anterior and posterior bands of paragnaths have rather different roles in feeding and suggest that the inter-population differences may be adaptations to different diets. The orientation of the jaws confirms that they play an important role only during predation and the handling of large particles, but not during the more usual browsing of the sediment surface.