Biochemical Genetics of Lobsters: Genetic Variation and the Structure of American Lobster (Homarus americanus) Populations

Abstract

Eight populations of American lobsters, Homarus americanus, were surveyed for genetic variation at 44 loci encoding electrophoretically detectable proteins. Rather low levels of genetic variability were found, the average proportion of heterozygous loci per individual being 3.8%. Genetic variation is concentrated at only eight loci, with just five loci — Acid phosphatase-1, Esterase-2, Phosphoglucose isomerase-4, Phosphoglucomutase-1, and Tetrazolium reductase-2 — having proportions of heterozygotes greater than 20%. Interpopulation differences are small; the genetic identity averaged over all loci, I, is above 0.99 in all but three comparisons. Differentiation between populations was found only at the Malic enzyme locus, but the degree of this differentiation supports the suggestion from previous migration and morphological studies that H. americanus is subdivided into a number of more or less geographically isolated inshore and offshore populations. These local populations are nonetheless genetically similar.