Geographical variation ion allozyme frequencies of populations of Penaeus monodon (Crustacea : Decapoda) in Australia

Abstract

This first systematic survey of genetic variation in P. monodon populations in Australia over a wide geographical range demonstrated highly significant differences in gene frequencies between the west-coast population and those on the northern and eastern coastlines. Some variation in gene frequencies among populations within the northern and eastern coastlines was detected in chi-square tests. Several loci (GPI*, PGM* and MPI*) contributed to the significant differences among populations. Genetic diversity decreased from east to west, suggesting colonization of the northern and western coasts by populations from the east after the last opening of the Torres Strait (c. 8000 BP). Evidence of genetic differences between western compared with northern and eastern populations is now available for three species of penaeid. These differences suggest, at least, that gene flow over several thousand years has been insufficient to erase genetic differences evolved during separation. Penaeid populations may therefore be more structured than has been thought, and the genetic homogeneity emphasized to date may be a result of the lack of genetic markers rather than a lack of population structure.