Razi University

Assessing and mapping the distribution and suitability of habitat is very important for the conservation and management of species. The viper Macrovipera lebetinus (Linnaeus, 1758) is a venomous snake species that is distributed in North Africa, parts of the Middle East and from the east to the Kashmir region. In this project, the effect of 19 bioclimatic variables and two geological variables over time (from 120 thousand years ago, 6 thousand years ago, present and future) on the distribution and suitability of the viper habitat will be investigated using the maximum disorder (MaxEnt) approach. The results of implementing the maximum entropy (MaxEnt) algorithm for the viper species indicate very high accuracy and excellent performance of the model in all time periods. A comparative study of time periods shows that the suitability of the viper habitat has experienced a decreasing and contracting trend from the "Last Interglacial and Middle Holocene" periods to the contemporary period. This decline in suitability in the contemporary period is due to a sharp decrease in the isothermal index (Bio3): a decrease from 26.9 to 11.5) and an increase in the seasonal instability of precipitation (Bio15), which indicates increasing climate irregularity. Also, the 31.5% contribution of the slope variable in the contemporary period indicates that the species has been pushed into specific ecological refuges with harsh topography due to the destruction of flat habitats by human activities. In contrast to the past decreasing trend, modeling for the 2080 horizon indicates a return and expansion of habitat suitability under both climate scenarios. In this evolution, the seasonality of temperature and precipitation of the coldest season of the year are the key drivers of change, which, by creating favorable “climate envelopes”, provide more optimal thermal and moisture conditions for this species in new areas and make the species susceptible to range shift. In order to assess the ecological relationships of the su  ecies, nest overlap and equivalence tests were performed based on Schoener’s D and Warren’s I indices. The results for su  ecies M. l. obtusa with M. l. turanica and su  ecies M. l. obtusa with M. l. cernovi showed that the hypothesis of ecological niche equivalence between the su  ecies was rejected. However, the results of the nest equivalence test between M. l. turanica and M. l. cernovi showed that there was no significant difference between the ecological niches of these two su  ecies. These results emphasize the ecological distinctions that have developed between the su  ecies over time and indicate complex competitive relationships and habitat isolation in this su  ecies complex. Overall, this study shows that the viper has undergone severe habitat fluctuations throughout the Earth’s climatic history. Although contemporary climate change has caused the species to contract its range and refuge in areas with harsh topography, future climate change (2080) could provide an opportunity to reclaim lost habitat and even expand into   ew areas. However, it should be noted that “climatic suitability” is only half the equation; the other half depends on the species’ ability to disperse and maintain connectivity between current and future suitable habitats. Given the increasing seasonal variability and unpredictable fluctuations, conservation management should focus on maintaining migration corridors so that the species can successfully range shift to new suitable areas in response to global warming.