Application of molecular genetic analysis in the differential study of fish populations in continental waters in order to identify population units of interest in management and conservation.This research area is basically aimed at the study of natural populations of endangered autochthonous species.Such it is the case of the study for identifying natural autochthonous common trout (Salmo trutta) populations and their differentiation from natural hybrid populations.These hybrid populations came from the introgression of exogenous genetic material caused by intense re-population campaigns in rivers with external-origin fish farm stocks.It also includes the study of natural autochthonous fish populations that are threatened by the destruction of their habitat, for example, the Spanish toothcarp (Aphanius iberus), the Valencia toothcarp (Valencia hispanica) or the three-spined stickleback (Gasterosteus aculeatus)