Phylogeography, speciation and conservation genetics of patagonian fishes

Our objective is to examine the comparative phylogeography of the native fishes of Patagonia. The uplift of the southern Andes beginning in the Miocene (ca. 23 MYA), separated east and west flowing drainage systems and influenced the phylogeographic patterns of the associated biota. The resulting phylogeographic patterns were subsequently affected by the recurring glacial and interglacial periods of the Pleistocene (1.8 MYA - 10,000 BP) and by volcanism. During the Last Glacial Maximum an ice sheet covered the Patagonian Andes along 1800 km from Lat. 35ºS to 56ºS. This ice sheet reached the edge of the continental shelf west of the Andes (Pacific) south of Lat. 42ºS. Genetic diversity for the Patagonian flora and fauna might therefore be expected to reflect a hierarchy of influences, with patterns of divergence from climate change and volcanisms during the Pleistocene and Holocene layered onto ancient divergence footprints produced by the Andean orogeny. We will focus on the phylogeography of the Galaxiidae, a group of fish represented in Patagonia by three widespread species: (Galaxias platei, G. maculatus, and Aplochiton zebra) and others of more restricted geographic distribution. G. platei is a landlocked species present in the deep waters of postglacial lakes. G. maculatus and A. zebra are small littoral species with G. maculatus exhibiting landlocked and diadromous forms. Phylogeographic patterns will be compared across the three species using mitochondrial and nuclear DNA loci. The application of statistical phylogeographic and coalescent methods on genetic data collected from various species within ecosystems will provide valuable insight into the evolution of ecological communities. The diversity of the Patagonian fish fauna is threatened by competition and predation by salmonids introduced during the early twentieth century, and more recently and more critically, by escaped aquaculture salmon, the influence of which is expected to increase with the ever expanding aquaculture industry in the region. Our research will prove useful for the development of knowledge based conservation and management priorities.