Geography Of Stream Salamander Lineages

Batrachuperus tibetanus, belongs to Amphibia, Caudala, Hynobiida, is an endemic species of China, mainly distributed in the Tsinling, Daba Mountain.and the eastern edge of Tibetan Plateau. These areas is not only the boundary of China climate between the north and south, but also the border line of the world animal geographic regionalization in Oriental and Palaearctic, it is the key region of physical geography and geographical regionalization. In the study, we research the molecular systematics and phylogeography of Batrachuperus tibetanus, to explore the influence on species differentiation because of the region climate and environmental changes in the quaternary period, and to infer to the geographical distribution pattern and formation process of the species.In the study, mtDNA Cytb gene754bp fragments as molecular markers, received a total of172individuals gene sequences of Batrachuper tibetanus from39populations, Using biological software respectively to carry out the sequence of analysis; Sequence variation and haploidtype distribution analysis; The genetic distances among populations analysis; Differentiation index and the analysis of gene flow between populations; the phylogenetic tree are constructed with maximum-parsimony (MP), maximum-likelihood (ML) and Bayesian inference (BI) methods of haplotype data; and Haplotype Median-Joining network is constructed. Molecular variation analysis, mismatch distribution analysis, neutral test, BSP and expansion test for all the clades; And estimate the expansion time of all clades; Based on two calibration methods estimate the divergence time of Batrachuper tibetanus. The results are as follows:1. In the sequences754sites, including601conservde sites,153variable sites (composed of122parsimony informative sites and31singleton site). Divides the haplotype for total of175Cytb gene sequences (including outgroup), total60haplotype.2. The genetic distance between populations shows:the genetic distance between0.1%～9.1%of39populations of Batrachuper tibetanus, the populations between the distribution in the Tibetan plateau and Qinba mountains with significant genetic differentiation. Differentiation index and gene flow analysis for Batrachuper tibetanus, the average value of Fst was0.7952, the degree of population divergence is high; the average value of Nm was0.7952, Gene flow among the populations was low. 3.With three method to construction of the phylogenetic trees of haplotype of Batrachuper tibetanus, the result shows that their topology structure and bootstrap valus was basically identical. Construction the Median-Joining network of haplotype sequences, the topology structure was identical with phylogenetic tree of haplotype sequences. In this paper, dividing the nine Clades for phylogenetic tree of haplotype of Batrachuper tibetanus, namely Clade l-Clade9, these Clades have definited local area in the geogeraphical diatribution. TangYu populations is the only groups distributed in the two Clades, in Cladel and Clade5has distribution, the overall genetic diversity was high.4. Genetic structure and Phylogeography analyisis for the clade of Batrachuper tibetanus, the result shows that the molecular variance mainly occurs within a clade, Phylogeography structure of the haplotype distribution pattern was significant. Mismatch distribution analysis shows that distributed in Tsinling and Daba mountain group experienced a demographic expansion in the past, and the population of distributed in the eastern edge of the Tibetan plateau region is relatively stable. According to the formula to calculate the expansion time, the expansion time of Cladel occured mainly in the last ice age (0.016～0.032Mya), other clade has experience the pleistocene period of quaternary ice age that before the last glaciation.(T>0.055Mya). Using two different calibration methods to estimate the divergence time, the divergence time between the nine clade is6.33～2.84Mya, the divergence time within the nine clade were began in time for the quaternary pleistocene period (T<2.48Mya), all populations had experenced the climate and environment change in the quaternary ice Age.In the process of populations expansion, Taibai mountain may be exist shelter in the quaternary glacial period, TangYu population is composed of surrounding population expansion. Wenxian Country、dabashan、Kuy、Pingheling populations, the divergence time was high that far from the Tangyu population, earlier differentiated from the clade within.In the quaternary glacial period, great snow mountain, qionglai mountain, minshan, taibai mountain, this high altitude mountains formed isolation for species expansion. After the ice age, low altitude and dryingValley, like the Hanjiang River Valley、Jialing River Valley and Zhenba Country formed isolation to the gene flow and subdivision between the populations of Batrachuper tibetanus.