Alcohol dehydrogenase in the marine polychaete Hyalinoecia tubicola: heterozygote deficit and growth

Abstract

1. 1. Gene frequencies for multiple alleles at two loci coding for the major NAD-dependent alcohol dehydrogenases (EC 1.1.1.1) were determined from a sample of 104 quill-worms Hyalinoecia tubicola (Polychaeta: Eunicidae). 2. 2. This sample, taken in 1981, was compared with a sample of 24 individuals, taken in 1967. There was no significant change in the frequency of the three major alleles at Locus I, although there was a significant difference for the frequency of the major alleles at Locus III. 3. 3. The highly statistically significant excess of double homozygotes, first observed in 1967, was again observed in 1981. There is no evidence for linkage disequilibrium among the 156 haplotypes which can be unequivocably identified, but there is a highly significant difference in gene frequency of Locus I alleles in the double heterozygote category as compared with the other categories. 4. 4. In both a freshly dredged sample and a sample maintained in laboratory sea-tables, heterozygotes were disproportionately over-represented in the upper third of the sample when scored for size. It is suggested that the deficit of certain heterozygote categories is the result of their greater growth potential making them more attractive to predators. 5. 5. The demonstration of a set of easily detected marker genes provides a useful tool for testing the extent to which H. tubicola is truly a cosmopolitan marine species.