Land use and climate change are affecting the abundance and distribution of species. The Trans-Mexican Volcanic Belt (TMVB) is a very diverse region due to geological history, geographic position, and climate. It is also one of the most disturbed regions in Mexico. Reptiles are particularly sensitive to environmental changes due to their low dispersal capacity and thermal ecology. In this study, we define the important environmental variables (considering climate, topography, and land use) and potential distribution (present and future) of the five Thamnophis species present in TMVB. To do so, we used the maximum entropy modeling software (MAXENT). First, we modeled to select the most important variables to explain the distribution of each species, then we modeled again using only the most important variables and projected these models to the future considering a middle-moderate climate change scenario (rcp45), and land use and vegetation variables for the year 2050 (generated according to land use changes that occurred between years 2002 and 2011). Arid vegetation had an important negative effect on habitat suitability for all species, and minimum temperature of the coldest month was important for four of the five species. Thamnophis cyrtopsis was the species with the lowest tolerance to minimum temperatures. The maximum temperature of the warmest month was important for T. scalaris and T. cyrtopsis. Low percentages of agriculture were positive for T. eques and T. melanogaster but, at higher values, agriculture had a negative effect on habitat suitability for both species. Elevation was the most important variable to explain T. eques and T. melanogaster potential distribution while distance to Abies forests was the most important variable for T. scalaris and T. scaliger. All species had a high proportion of their potential distribution in the TMVB. However, according to our models, all Thamnophis species will experience reductions in their potential distribution in this region. T. scalaris will suffer the biggest reduction because this species is limited by high temperatures and will not be able to shift its distribution upward, as it is already present in the highest elevations of the TMVB.

Barisia imbricata imbricata is an endemic anguid lizard living in the highlands of central Mexico, mainly in the Trans-Mexican Volcanic Belt, but its current distribution is not well defined. For this reason, it is critical to make a systematic study in order to determine the potential distribution of this subspecies. We considered 13 environmental and anthropogenic variables recognized to be important to determine the presence of B. i. imbricata ; we also used eight presence-only modeling methods and selected three to generate an ensemble model. The Maxent algorithm was used to obtain the most important variables. The variables with highest contribution to the model were: maximum temperature of the warmest month, altitude, Abies forest and Pinus forest. From the estimated potential distribution (9614.1 km ² ), 8053.4 km ² (83.8%) are located in the Trans-Mexican Volcanic Belt, 3821.4 km ² (39.7%) are located in natural protected areas and 2418.2 km ² (25.2%) are in crop fields. The whole potential distribution is highly fragmented and characterized by the presence of human activities, which could have long-term consequences, increasing extinction risk.

The dusky rattlesnake,Crotalustriseriatus, used to be very abundant in many parts of the highlands of central Mexico, but with the increasing human population and associated activities, the rattlesnake habitats and populations have suffered drastic reductions and fragmentation. At the moment, the most important habitat features, associated with the presence ofC.triseriatus, the current potential distribution and the landscape connectivity amongst the populations of the State of Mexico and Mexico City, are unknown. Therefore, we used the maximum entropy modelling software (MAXENT) to analyse the current potential distribution and most important habitat features, associated with the presence of the species. The variables with the highest contribution to the model were: proportion ofAbiesforest, minimum temperature of coldest month, maximum temperature of the warmest month, proportion ofPinusforest and annual precipitation. Furthermore, we found connectivity corridors only within mountain chains. Our results highlight the necessity for conserving the patches ofAbiesforest and preserving the populations ofC.triseriatusand the connectivity of the landscape.