American Society of Ichthyologists and Herpetologists, State College, Pennsylvania, July 2001.
Phylogenetic relationships, hybridization, and biogeography within the Australian pygmy perches (Percichthyidae).
P.J. Unmack, M. Hammer, M. Adams & T.E. Dowling
Pygmy perches are small freshwater fishes (rarely exceeding 10cm in length), with a restricted distribution in southeastern and southwestern Australia. Historically considered part of the Kuhliidae, and subsequently a unique family Nannopercidae, they have recently been included in the Percichthyidae, a decision supported by published 12S sequence data for percichthyids. This presentation summarizes the results of two companion molecular studies on the group, one using allozyme data at 50 loci to assess species boundaries in the group and population structure within widespread species, and the other examining relationships within Percichthyidae and among basal percoid families using mitochondrial and nuclear sequence data (cytochrome B, S7, RAG2). Both studies utilize many of the same specimens and include all pygmy perch species as well as an in-depth examination of the two most-widespread morphospecies N. australis and Edelia obscura. Although both studies are ongoing, several unequivocal conclusions are nevertheless evident. First, Nannoperca australis clearly comprises two species with largely parapatric distributions, but with a single instance of introgression in southeastern Victoria. Second, the specific status of all other named forms is supported. Third, all phylogenetic analyses of the mtDNA data indicate that the more-widespread species within N. australis is paraphyletic with respect to E. obscura, suggesting either that mitochondrial replacement has occurred between these species or that insufficient time has transpired for both species to move to reciprocal monophyly. Fourth, there appears little support for retaining Edelia as a separate genus. These results, and phylogenetic relationships of the group will be placed into a broader Australian biogeographic context.