Species Differation And Karyotype Analysis Of Crocidura Attenuata Cumplex

The grey shrew Crocidura attenuata and Taiwan grey shrew Crocidura tanakae are both white tooth shrew(Crocidura).While Crocidura attenuata is distributed in Southeast Asia and South China,Crocidura tanakae is endemic to Taiwan Island.The species differation of them are controversial for their similar morphological features and recent years,some molecular genetics researches revealed that Crocidura tanakae is also widespread in Vietnam,Laos and some sites of China.Therefore,in this study,we regarded all specimens in the same shape of Crocidura attenuata(including Crocidura attenuata.Crocidura tanakae and maybe some cryptic species)as Crocidura attenuata complex,and tried to solve the species differation problem of Crocidura attenuata complex.First,we captured 58 specimens in 14 sites of South China and did phylogenetic analysis based on their Cyt b gene.All specimens formed three independent cladees:A,B,C,which represtented Crocidura tanakae,a cryptic species firstly discovered(Crocidura sp.)and Crocidura attenuata,repectively.What is noteworthy is that they showed no sibling relationship in the phylogenetic trees and the genetic distance(K2P)between them is 11.8?13.6%,even greater than the genetic distance between some species in Crocidura,which all support these three as indepentdent species.Meanwhile,we found that Crocidura tanakae not only distributed in Taiwan,but also widespreed in 11 sampling sites of South China,at least.Crocidura attenuata is also widespread in South China and the cryptic species is restricted to southeastern coastal areas of China.Overall,these three species are sympatric in some sites of South China.Divergence time analysis showed that the first divergence happended in 2.92 Mya,and the differentiation and distribution of these three species are affected by the Quaternary Glacial.Population dynamics and the genetic diversity analysis showed Crocidura tanakae with high Hd,and low ? value.Neutral and Mismatch Distribution analysis also indicated that Crocidura tanakae had experienced rapid population expansion in the past.The population genetic diversity of Guangdong nanling is higher than other sampling sites,so we deduced Guangdong nanling as shelter during ice age of Crocidura tanakae and they may diffusion from here during interglacial stage.Meanwhile,the dynamic history of Crocidura attenuata and cryptic species is stable.We also analyszed thier karyotypes under the premise of identification accuracy by molecular methods.The results showed that Crocidura tanakae and cryptic species has karyotype polymorphism,while this interesting phenomenon hasn't been found in Crocidura attenuata.Crocidura tanakae has 4 kinds of karyotype,Al:2n=24-29=9?10(m+sm)+lst+1?2t+X(t)Y(t);A2:2n = 34 = 6(m+sm)+2st+8t+X(sm)Y(t);A3:2n=38=4(m+sm)+3st+11A+X(sm)X(sm);A4:2n=40=3-4(m+sm)+3st+13t+X(sm)Y(t).The cryptic species also has two kinds of karyotype,B1:2n=26=9(m+sm)+1st+3t+X(t)Y(y);B2:2n=40=3(m+sm)+3st+13t+X(sm)Y(t).Crocidura attenuata only has one kind of karyotype Cl:2n=40=3(m+sm)+3st+13t+X(sm)Y((t).We assumed tandem fusions and Robertsonian translocations is the main mechanisms of their karyotype polymorphism.Besides,we concluded that karyotype features cannot be used as an identification feature of Crocidura tanakae,Crocidura attenuata and the cryptic species because some specimens of these three species have same karyotype.