Genetic analysis of populations of north-western Australian fish species

Abstract

Allozyme variation was used to investigate the genetic structure of Lutjanus sebae, Lethrinus nebulosus, Lethrinus choerorynchus, and Epinephelus multinotatus, which are components of a multispecies fishery off north-western Australia. Samples of each species were obtained from five or six localities, over a total distance of 1400-2080 km. Allelic variation was found at 13-16 loci in each species. The consistent picture to emerge was one of little genetic subdivision in all four species, with average values of FST ranging from 0.003 in L. sebae to 0.012 in E. multinotatus. Although there was statistically significant variation in allelic frequencies in three of the species, there were no clear geographical groupings of populations. With the possible exception of clinal variation for aldehyde oxidase in E. multinotatus, all heterogeneity of allelic frequencies was within the range that could easily be due to within-generation effects of selection. Thus, the allozyme data are consistent with the view that there are extensive connections of populations over large distances. The electrophoretic study also confirmed that, contrary to suggestions in the literature, L. nebulosus, L. choerorynchus, and Lethrinus laticaudis are reproductively isolated species.