Holocene biogeography of the southwestern European white‐toothed shrew (Crocidura iculisma, Eulipotyphla) through its fossil record

Abstract

Crocidura iculisma (=C. suaveolens) is a shrew (Soricidae, Eulipotyphla) showing a fragmented distribution limited to the Iberian Peninsula, southern and western France and northwestern Italy. Although it has been in the Iberian Peninsula since the Middle Pleistocene, its biogeographical history remains poorly known. Here, we provide new data on Crocidura iculisma from the Castillejo del Bonete site (southern Spain) dated as 3.8–3.6 cal kyr BP. At the same time, we analyse changes in its geographic distribution based on its palaeontological record. We have reviewed thoroughly the Holocene record of Crocidura iculisma in southwestern Europe, considering independently the three time intervals according to the stages defined for this geological time series (Greenlandian, Northgrippian and Meghalayan). Whenever found together in fossil sites, the relative abundance of the two sympatric shrews of the genus Crocidura (Crocidura russula and Crocidura iculisma) was analysed. The data obtained concerning past distribution range and relative abundance were compared with the current status of the species in Iberia to interpret changes through time. The distribution range of the southwestern European white‐toothed shrew in the Iberian Peninsula has notably reduced over time until today. The occurrence at Castillejo del Bonete and other palaeontological records located beyond its current distribution range show that it was distributed in several areas of the eastern part and southern interior of Iberia, at least until the second half of the Meghalayan. Relative abundance patterns observed in the fossil assemblages suggest that competitive exclusion by Crocidura russula and climatic changes played a crucial role in driving the extirpation of Crocidura iculisma from a substantial portion of the Iberian Peninsula.