American Society of Ichthyologists and Herpetologists, New Orleans, LA, July 2006.

A test of vicariant patterns in southeastern Australia in multiple sympatric Hypseleotris species.

C. Thacker & P.J. Unmack

A key tenet of vicariance biogeography is that species with similar distributions should show congruent biogeographic patterns. Here we test this hypothesis in southeastern Australia in the genus Hypseleotris with a phylogenetic analysis using cytochrome b for 179 individuals from five species. Three or four Hypseleotris species are usually sympatric within each of three biogeographic provinces: Eastern (EP), Murray-Darling (MDP) and Central Australian (CAP). At many localities it is possible to collect all three or four species within the same seine hauls. Each species has broad environmental and physiological preferences which allows them to be abundant and broadly distributed. Phylogenetic analysis resolves the five species into four major groups: two clades of H. klunzingeri, one consisting of individuals from EP, plus two northern MDP localities, and the other including the remainder of MDP localities, along with CAP individuals. The other two clades include a mixed H. galii/H. sp. 3 Murray-Darling clade, with EP and MDP lineages mostly segregated and differentiations in populations spread along EP, and a mixed H. sp. 4 Lake's and H. sp. 5 Midgley's clade, with a more mixed phylogenetic distribution of geographic localities. Additionally, three H. sp. 3 Murray-Darling individuals fall outside their primary grouping, indicating the possibility of mitochondrial introgression among species, and/or retained ancestral polymorphisms in some H. sp. 3 Murray-Darling populations. The overall picture demonstrates that despite their common distributions, each species has its own unique biogeographic pattern, suggesting that the causes of biogeographic movement within each species did not effect each species equally. Alternatively, it may also be possible that each species undertook similar movements, but there was uneven persistance of their genotypes.