Population Genetic Structure Based On Mitochondrial Genes NAD1 And COX1 In Baylisascaris Schroederi

Giant panda (Ailuropoda melanoleuca) is one of the most endangered species in the world. Affected by climate change, anthropogenic activities and its own factors such as physiological limitations, three distinct genetic clusters-Qinling, Minshan and Qionglai-Daxiangling-Xiaoxiangling-Liangshan among the current panda population were split. The expansion, contraction and migration of host population determines the parasite population structure and genetic differentiation. Baylisascaris schroederi is the most serious parasite in giant panda. To obtain the basic data of epidemiological, evolutionary biology, and resistant mechanisms of Baylisascaris schroederi, we analysed population genetic structure of Qinling, Minshan and Qionglai geographic populations using mitochondrial NAD1 and COX1 gene as molecular markers. The mainly research work as follows:1. Population genetic structure based on mitochondrial genes NAD1 in Baylisascaris schroederiTo explore population genetic structure in B. schroederi from different mountains, 47 complete sequences of NAD 1 (Minshan 13, Qionglai 26, Qinling 8) with the length of 873bp were sequenced and analysed.47 samples which from three geographical populations were separated into 15 haploid type; the global haplotype diversity (Hd) and nucleotide diversity(Pi) were 0.8529±0.035 and 0.003378±0.001999 respectively; Tajima’s D and Fu’s Fs neutral inspection of total population was significant and negative; demographic analyses displayed unimodal; AMOVA analysis suggested that genetic variation within populations was larger than that between populations, indicating that genetic divergence was mainly distributed within populations; NJ tree of haplotypes and haplotype network graph suggested that there was no direct correlation between phylogeny of three populations and georaphical regions; non-significant Fst values and high gene flow suggested that there was no significant genetic differentiation among three geographical populations. Experiments show that B. schroederi appeared population expansion in the process of evolution; The genetic variability of populations in B. schroederi was low, and genetic divergence was mainly distributed within populations; Differentiation between populations was not obvious, and the three geographical populations of B. schroederi belong to the same population.2. Population genetic structure based on mitochondrial genes COX1 in Baylisascaris schroederiTo explore population genetic structure in B. schroederi from different mountains, 56 complete sequences of COX1(Minshan 19, Qionglai 33, Qinling 4) with the length of 1578bp were sequenced and analysed.56 samples which from three geographical populations were separated into 24 haploid type; the global haplotype diversity(Hd) and nucleotide diversity(Pi) were 0.9364±0.0168 and 0.002547±0.001433 respectively; Tajima’s D and Fu’s Fs neutral inspection of total population was significant and negative; demographic analyses displayed unimodal; AMOVA analysis suggested that genetic variation within populations was larger than that between populations, indicating that genetic divergence was mainly distributed within populations; NJ tree of haplotypes and haplotype network graph suggested that there was no direct correlation between phylogeny of three populations and georaphical regions; non-significant Fst values and high gene flow were detected between the Qinling populations and both the Minshan populations (Nm=3.84) and Qionglai populations (Nm=4.19), while higher gene flow were found between the Minshan and Qionglai populations(Nm=21.92). Experiments show that B. schroederi appeared population expansion in the process of evolution; The genetic variability of populations in B. schroederi was low, and genetic divergence was mainly distributed within populations; Differentiation between populations was not obvious, and the three geographical populations of B. schroederi belong to the same population. The results also indicate that mitochondrial COX1 gene was effective molecular markers in the study of population genetic structure.