Genetic and morphological diversification of Galaxias maculatus in Northern Patagonia

CARREA, CECILIA; BARRIGA, JUAN; CUSSAC, VÍCTOR; RUZZANTE, DANIEL

Bariloche

Congreso; VI Southern Connection; 2010

CONICET, Universidad Nacional del Comahue, INTA

Objectives: To study the influence of life history, ecology and history on the diversification of G. maculatus in Patagonia. We hypothesized that restrictions in gene flow may lead to local adaptation and population divergence. Methods: Patterns of genetic, morphological and meristic variability in G. maculatus were examined using microsatellites, geometric morphometrics and meristic counts. Eleven localities differing in connectivity were sampled within Lakes Nahuel Huapi, Correntoso and Victoria Island. Results: A bayesian analysis identified K=4 genetic clusters, corresponding to localities in Victoria Island (2), Correntoso Lake (1), and Nahuel Huapi lake (1). Morphology and genetics were correlated with each other but neither was correlated with geographical distance. G. maculatus from Lake Redonda exhibited lower genetic diversity, lower meristic counts and different morphology than the other locations. No genetic or morphological structure was detected within Nahuel Huapi or Correntoso lakes. Conclusions: G. maculatus within Redonda Lake has likely been isolated since the drop in water level of a paleolake , ca. 16.000 BP. Divergences of Larga and Correntoso populations are explained by life history and predator presence in the streams connecting them with Lake Nahuel Huapi. Finally, the lack of genetic structuring within Nahuel Huapi and Correntoso lakes suggests this species larval limnetic habit exerts an important homogenizing effect on gene flow within lakes.