Documenting the biogeographic history of Microtus cabrerae through its fossil record

Abstract

1. Microtus cabrerae is an Iberian endemic vole species with specific adaptations to the subhumid mediterranean climate. Its living populations are under a regressive trend. The earliest known records of Microtus cabrerae date from the late Middle Pleistocene, and it originated from Microtus brecciensis. 2. We describe changes in the geographic distribution of Microtus cabrerae throughout its history based on its palaeontological record, and to link them to environmental changes that have taken place since the appearance of Microtus cabrerae. 3. A series of successive chronological intervals comprising the recorded existence of the species was established, so that the majority of the published fossil records of Microtus cabrerae could be used for analysis. For each interval, a map with the inferred distribution of the species was created. The maps were used to establishing variations in the species’ distribution through time. Biogeographic history of Microtus cabrerae 2 4. A first regression in the extent of the distribution of Microtus cabrerae took place in Marine Isotope Stage 2, when the species abandoned south-eastern France and central Spain, where it had been present since the beginning of the Late Pleistocene. This range contraction was probably due to the global decline in temperatures and rainfall that took place in this period. After a rapid recolonisation of most of the previously abandoned areas at the beginning of the Holocene, and a remarkable increase in records during the Neolithic, a new gradual decrease of records is observed from the Neolithic to the Roman period, intensifying from ca. 2000 years ago onwards, and ending with the final disappearance of the species from south-western France and north-eastern Iberia. This second decline is linked to the aridification of the Mediterranean entourage that started in the mid-Holocene and has been enhanced by human modification of the landscape. The species is shown to be sensitive to climate change.