Comparative study of bechstein¿s bats in contrasting climatesthe legacy of forest transformations

Resumen

Myotis bechsteinii is a European forest bat species. Although widely distributed, it's considered rare and only locally abundant over its entire range. Current rareness- in strong contrast to the abundance in the fossil register- and its distribution restricted to large masses of deciduous forest in good conservation status, suggest that Myotis bechsteinii is retreating, as a consequence of climatic factors, deforestation or both. Data on local abundance in the Iberian Peninsula contradict expectations based on current knowledge about ecology and distribution of the species, and raises the need for a revision of its ecological constraints, and for a comparison in contrasting climatic domains. The comparative study conducted shows that the ecological niche of the species is conserved across its distributional range. Furthermore, it does not support the vision of the Mediterranean area as suboptimal for the species, but rather the opposite. Thus, the reported scarcity of the Bechstein's bat in the area seems to be more related to degradation and rarefaction of preferred habitats- deciduous forests- than to bioclimatic conditionings. Genetic structure also reflects the prolonged isolation of Mediterranean populations, attributable to the secular deforestation, except in the cases where low altitude mountains acted as corridors promoting connectivity. The unexpected scarcity of the Bechstein's bat in the centre- north of the Peninsula may also relate to the intensive management of the territory. Given the slow and limited responsiveness of Myotis bechsteinii to perturbations to their habitat or populations, the present distribution- smaller than the potential habitat- may reflect the history of fragmentation and degradation of forests. This vision is supported by the genetic structure of the involved populations.