Subterranean Fishes of the World

3200

2013

AIM 2013

The Mexican tetra, Astyanax mexicanus is successful species with high capacity to dispersion and adaptation to different habitats, including aquifers. Along its range this species have two morphtypes; a normal epigean and a blind hipogean, this last one without eyes or pigmentation and habiting aquifers in Northeastern of Mexico. The morphological monotony a long its range had raised confusion on specie’s taxonomic status. The most studies of population genetic in Astyanax mexicanus have focused primarily on populations of cave and near of these, and the incomplete sampling along the Atlantic slope of Mexico, can lead to wrong interpretations. Using a battery of 10 microsatellite loci and increased sampling coverage along of hydrological basins the Atlantic slope, we study the genetic diversity, structure and genetic relationships between different localities of Astyanax, including samples of Bromocharax caballeroi from Catemaco Lake. In the north the individuals were taxonomically identified as Astyanax mexicanus, while those from south were Astyanax aeneus, however the genetic distances between them do not support such separation. The individuals from Catemaco Lake showed morphological characteristics and genetic distances similar of Astyanax, so it appears to be a variant in Astyanax. Various analyses (AFC, FST, AMOVA and STRUCTRE) detected 10 genetically homogeneous populations, where the caves populations showed higher levels of differentiation and genetic distances than the surface populations. The surface populations near to the caves showed lower degree of divergence from the southern populations than with the caves populations, these could indicate two waves of invasion from south to north as was proposed previously by others. The dendrogram constructed with genetic distances (DCE) confirm these results. For the first time in genetic studies, we add locations north of the caves, with this data we observed that the caves populations are an intermediated group between northern and southern populations, besides the fact find the isolation by distance among northern populations and the correlation of these with each one the southern populations, we propose a third wave invasive south-north direction in recently time, so the Tans-Mexican Volcanic Belt no appears to be a geographical barrier for Astyanax dispersion as it has been for other species. Finally the individuals of Catemaco showed low values of genetic differentiation with regard to northern populations of Garza Valdez/Troncones, probably due to an ancestral genetic signal or translocation by human. Key word: Astyanax mexicanus, microsatelites, population genetic.

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