Post-Pleistocene evolution of Bornean shrews Crocidura foetida (Mammalia, Soricidae)

Abstract

Fossil mandibles of the Bornean shrew Crocidura foetida recovered from excavations at the west mouth of Niah cave, Sarawak, Malaysia, show that the late Pleistocene population at this lowland location was comparable in size with the large subspecies Crocidura foetida doriae, presently occurring at inland, upland locations. Two Holocene specimens fall in the size range of the smaller lowland subspecies C. f. foetida. Comparable post-Pleistocene size-reduction is known among other mammals of Borneo, but this is the first instance of dated examples. The evolutionary trend conforms with Bergmann's 'rule' but, other than climate change, no selective agent is apparent.