Abstracts (first author)
Phylogeographic analysis of the Mexican freshwater fish complex Catostomus nebuliferus-plebeius
The complex Catostomus nebuliferus-plebeius is endemic group of fish Northwestern Mexico (C. nebuliferus y C. plebeius), member of the Catostomidae family distributed in North America. The complex is distributed in basins of Sierra Madre Occidental: Catostomus nebuliferus in the Nazas river; while C. plebeius is distributed in the Mezquital, Piaxtla, Fuerte, Yaqui, Conchos and internal basins derived from the Guzmán lagoon. Therefore the origin and activity of this mountain system should be associated to the evolutionary history of the complex. The first plausible scenario is where this mountain serves as a center of diversification. The second scenario would be that the current distribution of complex is resulted of admixture between populations isolated in the lowlands to the west and east of the mountain during the Pleistocene interglacials states. We implemented phylogeographic, phylogenetic and population genetics analysis to describe the evolutionary history of complex. High genetics distances were found in preliminary results between all populations of the complex (3-5% with Cytochrome b mitochondrial gene) and high genetic diversity in each population, indicative of an ancient isolation. A process of isolation occurred ~5.7 millions years ago in the Pliocene, isolating the population of Nazas and Mezquital of the North basins, resulted of the geological events of the region; while in the same period (~4.5 millions years ago) were separated populations from Mezquital river and C. nebuliferus populations. The populations of C. plebeius of the north basins were isolated gradually during the last 4 millions years describing a South-North isolation pattern associated to a geological activity. Null migration rate was estimated between populations after isolation discarding of river piracy in the Pleistocene. Our results have taxonomic and conservation implications, because the complex currently consists of several independent evolutionary lineages.