SUMMARY
The current study proposes two methodological approaches for analyzing the effects of climate change on biodiversity, one at the level of bioclimatic zone, and the other one at the species level. Three general circulation models were applied to nine bioclimatic zones and 61 species of mammals in México for the 2050 time horizon: ECHAM5/MPI, UKHADGEM1 and GFDL CM 2.0, each one with two emissions scenarios, A2 and B2. In the case of bioclimatic zones a multinomial logit model was used based on data from surveys of vegetation, climate data and soil information in order to obtain probabilities of occurrence. In the case of mammals, ecological niche models were made for each of them as well as models of their distribution in the country within each bioclimatic zone. The results show that ECHAM and Hadley coincide with tendencies towards drier conditions mainly in northern México, in contrast with GDFL with less severe results. Differences are noticed according to the applied emission scenarios. Results at a specific level coincide roughly with their corresponding bioclimatic zones. By 2050 it is generally expected that almost half of all analyzed species will lose around 50% of their area of distribution as a result of the impact of climate change.