Reproduction and population genetics of the New Zealand brooding brittle star Ophiomyxa brevirima

Abstract

A study of the reproductive mechanism of the brooding brittle star Ophiomyxa brevirima (H. L. Clark) was first undertaken. Isozyme electrophoresis was employed to uncover the genetic relationship of parent to offspring, aiding interpretation of the observed genetic structures of populations separated by geographic distance. The genetic structure of four intertidal populations of this ophiuroid was investigated by examination of variation at seven polymorphic loci. Mean levels of heterozygosity ranged from 0.238 to 0.332. Hardy-Weinberg equilibrium was observed at all but one locus in all populations. Values of Nei's unbiased genetic identity (I), distance (D) and standardised genetic variation between populations (F(ST)) were used to analyse the connectedness of populations assessed. These values suggested moderate connectivity between populations. Measures of genotypic diversity were used to interpret the degree of clonal structuring within each population.