我国华南中麝鼩分子系统地理学分析

Molecular Phylogeographic Analysis of Chinese White-toothed Shrew in China

华南中麝鼩(Crocidura rapax)亚种分化存在异议。为了明确我国华南中麝鼩的分子系统地理格局,为其分类学提供进一步分子生物学证据,测定了我国贵州华南中麝鼩20个样本的Cyt b基因序列,并结合GenBank下载的19个华南中麝鼩Cyt b基因序列进行一并分析。结果表明:系统发生树首先分成3个大的进化支,即华南中麝鼩华南亚种(C.r.rapax)进化支、西南中麝鼩(C.vorax)进化支、华南中麝鼩台中亚种(C.rapax kurodai)进化支。华南中麝鼩华南亚种分成贵州、云南、四川东南部谱系和四川中西部谱系。遗传距离结果发现,最大遗传距离出现在华南中麝鼩华南亚种四川中西部谱系与华南中麝鼩台中亚种之间(0.1181),其次是华南中麝鼩华南亚种贵州、云南、四川东南部谱系与华南中麝鼩台中亚种之间(0.1174)。华南中麝鼩华南亚种2个谱系间遗传距离为0.0195。中介网络分析也观察到相似分化格局。中介网络图的结果与系统发育关系和遗传距离的结果一致,支持来自台湾地区的华南中麝鼩样本为独立物种的观点,即台湾长尾麝鼩(C.tadae)。我国华南中麝鼩无亚种分化,分为贵州、云南、四川东南部谱系和四川中西部谱系。在华南中麝鼩的32个样本中发现23个单倍型,核苷酸多样性0.01285。种群历史分析暗示华南中麝鼩近期尽管经历了种群扩张,但并非为单次急剧扩张。

Subspecies differentiation of Chinese white-toothed shrew(Crocidura rapax)is controversial.In order to clarify the molecular phylogeographic pattern of C.rapax and provide further molecular biological evidence for taxonomy,this study analyzed the Cyt b gene sequences of C.rapax(20 samples)collected from Guizhou Province in China together with Cyt b gene sequences of C.rapax(19 samples)downloaded from GenBank.The phylogenetic tree was divided into three main clades:C.r.rapax,C.vorax,and C.rapax kurodai.The C.r.rapax is divided into Guizhou,Yunnan,southeast Sichuan lineage and central and west Sichuan lineage.The results of genetic distance showed that the greatest genetic distance was between central and west Sichuan lineage of C.r.rapax and C.r.kurodai(0.1181),followed by between Guizhou,Yunnan,southeast Sichuan lineage of C.r.rapax and C.r.kurodai(0.1174).The genetic distance between two lineages of C.r.rapax is 0.0195.A similar geographical patterns was also observed in the median-joining network analysis.The results of median-joining network are consistent with the results of phylogenetic relationships and genetic distance,supporting the view that the sample from Taiwan is a separate species,namely,C.tadae.The C.rapax have no subspecies differentiation in China,and can be divided into Guizhou,Yunnan,southeast Sichuan lineage and central and west Sichuan lineage.Twenty-three haplotypes were found in the 32 samples of C.rapax,and the nucleotide polymorphism was 0.01285.The analysis of population history suggested that C.rapax has experienced population expansion recently,but it is not a single dramatic expansion.