Population Analysis Based on Mito-nuclear Sequences: Implication of Dugesia japonica Decline in Taihang Mountains, China
Population Analysis Based on Mito-nuclear Sequences: Implication of Dugesia japonica Decline in Taihang Mountains, China
He-Cai Zhang, Tian-Ge Hu, Chang-Ying Shi, Guang-Wen Chen* and De-Zeng Liu
ABSTRACT
Freshwater planarian Dugesia japonica is widespread in East Asia and has been used as a model animal in many research fields. Taihang Mountains is the demarcation line and indispensable treasure house of natural resources and ecological barrier in North China. In order to explore the genetic diversity, genetic structure and demographic history of D. japonica in Taihang Mountains, the mitochondrial Cytb and nuclear ITS-1 sequences of 120 individuals from 20 populations were analyzed. The results showed that 46 haplotypes were detected in total, including 10 shared haplotypes and 36 private ones. The overall haplotype diversity (Hd) and nucleotide diversity (π) were 0.961 and 0.00157, respectively. The phylogenetic relationship and haplotype network analysis indicated that there was no obvious correspondence between the haplotypes and the geographical locations, revealing no obvious phylogeographic pattern. Analysis of molecular variance (AMOVA) suggested that the genetic differentiation of D. japonica in Taihang Mountains was very great (FST=0.405, P<0.01). This significant genetic variation mainly occurred within populations (59.52%), followed by 36.54% deriving from among populations. As for demographic analysis, positive Tajima’s D and Fu’s Fs values (0.250 and 1.657, respectively) were found in concatenated Cytb/ITS-1 sequences as a whole for neutrality test. Moreover, the mismatch distribution was multimodal. Therefore, D. japonica in Taihang Mountains might have been undergoing a population decline, and conservation measures such as reducing human interference should be taken. We hope these findings will arouse conservation and management strategy regarding freshwater planarians and contribute to the biodiversity in the long run.
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