Geographical patterns of genetic variability in introduced Australian populations of the marine toad,Bufo marinus: Sorbitol dehydrogenase,Sdh

The marine toad, Bufo marinus, was introduced to Australia from Hawaii in 1935. From 1935 to 1974, the toad population expanded exponentially to occupy 584,000 km², and now has a continuous distribution from Cape York to Tweed River on the eastern coast of the continent. Genetic analysis of the population indicates a difference in allele frequency at the sorbitol dehydrogenase locus. There are two alleles segregating at the locus (NAD-Sdh^a and NAD-Sdh^b). The NAD-Sdh^aa homozygote is common in the two southern populations, but uncommon in northern populations. The north-south difference has been established in less than 25 generations.