Modelling the past and future distribution of contracting species. The Iberian lizard Podarcis carbonelli (Squamata: Lacertidae) as a case study

While glaciations constituted the major recent paleoclimatic event, inducing multiple oscillations on species’ ranges, future and rapid shifts are expected if global warming predictions are confirmed. Investigating the whole temporal spectrum of range shifts is of conservation importance since species suffering contractions during the interglacial periods may continue contracting in a warming scenario; lizards provide excellent models for such analysis. We investigated the historical biogeography of Podarcis carbonelli, a lacertid lizard endemic to the Western Iberian Peninsula with a fragmented distribution, likely resulting from an important reduction during the Pleistocene and Holocene. We modelled with Maxent its current distribution and projected it to past (Last Interglacial—LIG and Last Glacial Maximum—LGM) and future (2020, 2050 and 2080) scenarios. The consensus models predicted a larger suitable area than the currently occupied, in areas with a high humidity and low maximum temperatures. The LIG model indicated a reduced range restricted to the northern Portuguese coast, and the LGM model, a suitable area larger than the current. After the LGM, areas with suitable climate started regression till present, which is predicted to continue in future, with a northward range shift and a loss of suitable climate from inland zones towards the coast. The range of P. carbonelli may have been oscillating from the northern Portuguese coast to the south and to inland during the Pleistocene. The Portuguese West Atlantic coast, harbouring a substantial part of the species’ genetic diversity, with suitable climate during the LIG and LGM and forecasted to remain in the future, is not currently protected but deserves conservation priority.