Genetic differentiation and zoogeography of Asian Suncus murinus (Mammalia: Soricidae)

Abstract

Protein electrophoresis was used to assess the phylogenetic relationships of populations of the phenotypically variable Asian house shrewSuncus murinus. These populations represent a sample of both commensal and wild forms. They were compared to another taxon,S. montanus, which was formerly considered conspecific withS. murinus. Suncus dayiwas used as an outgroup in all phylogenetic reconstructions. Within theS. murinuslineage, the allozyme data show very low levels of genetic differentiation among both wild and commensal Southeast Asian and Japanese samples when compared to the Indian populations. This pattern is consistent with the classical hypothesis of a recent introduction by man in Eastern Asia. The higher genetic diversity found withinS. murinusfrom India, as well as previous mitochondrial and karyological results suggest that this area is the probable centre of origin for the species. Although the lack of gene flow betweenS. murinusandS. montanusis clearly established in an area of sympatry in Southern India, one Asian house shrew sampled in Nepal was more closely related toS. montanus. This could either reflect the retention of an ancestral polymorphism, or result from a hybridization episode betweenS. murinusandS. montanus. Similar conclusions were also suggested in mitochondrial DNA studies dealing with animals sampled in the Northern parts of the Indian subcontinent. Clearly, further data onSuncusfrom this area are needed in order to assess these hypotheses.