Modelling a species in expansion at local scale: is <i>Hyla meridionalis</i> colonising new areas in Salamanca, Spain?

Abstract

New records of the frog Hyla meridionalis have been reported in the province of Salamanca (Spain). However, it is not clear if those records correspond to an expansion process or to a lack of sampling. Thus, the species range was modelled in order to identify which is its potential distribution, which areas are available for expansion, and which variables drive the distribution. Ten MAXENT iterative models were produced at 1×1 km scale. The suitable areas in Salamanca occurred only in the south-east part of the province. This area corresponds mainly to the Alagón river basin, together with a small part of the Tormes river basin. The presence area was 1040 km², meanwhile the absence one corresponded to 11309 km². The models indicated a strong relationship with temperature and precipitation factors. Predictive models cannot confirm or reject the expansion process of the species. Then, H. meridionalis could be in equilibrium (or nearly) with the environment and may not spread further, or in expansion, but the process is almost complete. If the species is not in expansion, new records recently obtained in Salamanca could be the consequence of previous lack of sampling. Also, the expansion speed could be very low to be detected in human time-life.