Mitocondrial phylogeny and biogeographical scenario of Asiatic water shrews (genus Chimarrogale) : implication for taxonom and low latitude migration route

抄録

 The six species and three subspecies in the genus Chimarrogale ( Soricomorpha: Soricidae) called Asiatic water shrews. Chimarrogale is the most widely distributed group of Nectogaline shrews, extending throughout the Oriental region and Japan. Because of limited numbers of specimens, the phylogenetic relationships and biogeographical history of this genus have not been discussed comprehensively. We used mitochondrial cytochrome b gene sequences to estimate phylogenetic relationships and divergence times among four Chimarrogale species including all three subspecies of Chimarrogale himalayica. We also conducted the species delimitation analysis and test two alternative migration scenarios in Asia using ancestral distribution.reconstruction and species distribution modeling. We provided the first-ever phylogenetic hypothesis of the Asiatic water shrew and revealed 10 putative species within the four recognized species. Distinct phylogenetic status for Chimarrogale phaeura, Chimarrogale platycephala and Chimarrogale styani were confirmed. Chimarrogale himalayica was strongly supported as paraphyletic. We suggest Chimarrogale himalayica leander of southeastern China should be considered as Chimarrogale leander. There are three more putative species.distributed in central southwestern China and Taiwan are currently undescribed and therefore, comprehensive morphological analyses are warranted to test their taxonomic statuses. Estimated molecular divergence times.indicated rapid speciation occurred during the early Pliocene. Current distribution pattern may have been affected by followed global cooling during the Pliocene/Pleistocene boundary. Ancestral distribution reconstruction and species distribution modeling for Asiatic water shrews revealed low latitude migration route in which ancestral Chimarrogale migrated from Europe via Central Asia to the current distribution. Our results demonstrated that Asiatic water shrews could evolve throughout low latitude migration route from Europe to Asia continent.