Desert Fishes Council, Cuatro Cienegas, Coahuila, November 2008.

Phylogeographic patterns within the central Australian rainbowfishes.

P.J. Unmack, M. Adams & T.E. Dowling

Phylogenetic patterns within Australian desert fishes remain relatively poorly known, although considerable research is underway to investigate the systematics and biogeography of this unusual fauna. A phylogeographic study was recently completed on one of the more abundant groups, the rainbowfishes (Melanotaeniidae: Melanotaenia) as part of a broader Australia wide examination of the group. Two species occur in the eastern arid portion of Australia, Melanotaenia fluviatilis in the Murray-Darling Basin and M. splendida tatei which occurs in western portion of Murray-Darling Basin and the Lake Eyre Basin. We used SSCP to determine variation in a portion of the mitochondrial cytochrome b gene and allozyme electrophoresis on 18 variable loci to examine phylogeographic patterns. Results suggest that central Australian rainbowfishes have a complicated history, with several potential invasions into the Lake Eyre Basin from surrounding drainages. In addition, M. s. tatei appears to have recently invaded the Murray-Darling Basin and a hybrid zone now exists where they come into contact with M. fluviatilis. The history of M. fluviatilis is also complicated by introgression with M. duboulayi, a species found in eastern coastal drainages. This work adds to the growing body of evidence that hybridization and introgression in rainbowfishes may be more common than previously thought and has important implications at multiple temporal and spatial scales.