| The Qinling-Daba Mountains area, the most important boundary of fauna in China, is consisted of Qinling Mountains, Daba Mountains and Hanjiang River Valley. It has divided oriental realm and palearctic realm. The Qinling Mountains is located in warm temperate climate zone, and the south of it has a subtropical climate.It is one of the most diversity habitat in China. This area connect the Qinghai-Tibet plateau and Shanxi plateau, facilitated the exchange of species from north plateau. Hanjiang River and Danjiang River flow into Yangtze River towards the south of China, rendered the species from South China have a chance to enter into Qinling-Daba Mountains area. All these evidences demonstrated that Qinling-Daba Mountains area is a vital transition zone of fauna in China, merged both north and south species. And the species distribution patterns here are influenced by several geographic events, such as repeated Glacial and interglacial periods, especially the Quaternary climate fluctuation.Oxya intricata(Stal.) were generally found in humid environment and feeds on some graminaceous species particularly on rice (Ma et al.2002). The moist climate condition and the lower elevation in basin and valley are the major influences towards the distribution of Oxya intricata(Stal.). In addition, Oxya intricata(Stal.) is capable of flying but not preponderant. Therefore, the interflow among the populations may be low and easy to form a stable population. That is the advantage of genetic differentiation study in a small spatial scale. The epiproct of Oxya intricata(Stal.) has some typical and stable points at the base of longitudinal sulcus, the base of furcula, the top and the base of lateral margin, the end of lateral sulcus, the top of epiproct and the top of lateral margin of longitudinal sulcus. That is the prior condition for geographical morphology study for selecting landmark and the useful preparation for the further study.In the phylogeography and population genetics aspects, this study select mitochondrial COI gene as DNA marker to discuss the genetic relationship among13Oxya intricata populations (123individuals) in Qinling-Dabashan Mountains, and infer the demographic history of populations to estimate whether bottlenecks and the expansion of populations were exist in this area, moreover, deduce the evolutionary history of Oxya intricata(Stal.) based on population coalescent time. The results are listed as follow:1. We obtained123sequences of Oxya intricata(Stal.) population. The length of this fragment of partial COI gene was729bp, there were81polymorphic sites with32variable sites.2. All the population mainly shown a high diversity of haplotypes, a low diversity of nucleotides and a close relationship of genetic distance. AMOVA indicated that the level of genetic differentiation is general (FST=0.14266), and a high genetic differentiation is among haplogroups (FST=0.6815). With the regard of geographical distribution, we can infer that populations were influenced by both geographical distance and vicariance. Mantel test revealed a significant pattern of IBD, but several population have no significance between genetic differentiation and geographical distance, therefore, populations might be affect by vicariance at the time.3. There was no apparent phylogeographical relationship among Oxya intricata populations. According to3phylogenetic tree, combining with geographical distribution and the bootsrap confidence level of clades, we can divide the populations into7haplogroups. Meanwhile, haplogroups could be separated into3geographical groups: Hanjiang River Basin group(consist of haplogroup D and F), the south of Ankang Basin group(consist of haplogroup B and G) and the north of Ankang Basin group(consist of haplogroup C and E). But the haplogroup in respective geographical group had a distant evolutionary relationship, thus probably complex events had occurred inner group.4. Mismatch distribution presents unimodal curves in all haplogroups, that indicated that population had experienced fast expansion, and occurred during0.1906-0.0513Myr. XY population expanded later relatively, Hanjiang River Basin group had endured repeatedly expansion and extinction, and the two geographical group of Ankang Basin had a early expansion time more likely to be the refuge of glacial period.5. tMRCA for all haplotypes of Oxya intricata was estimated to0.7525Myr, the coalescent time of every haplotype was occurred in the Middle and Late quaternary glacial period. The XY population is likely to be a relatively new population, evoled from Ankang Basin. They might be affect by glacial period, and moved to Ankang Basin for refuge, at that time geneflow was frequently, then they moved to XY area and fixed with experiencing the founder effect. The coalescent time of Hanjiang River Basin group is early, which contain4general distribution haplotypes (H33, H42, H13and H16), so it should be the relatively old population. The north of Ankang Basin group had abundant haplotypes, it contained the most widely spread haplotype H1and several haplotypes of XY population, therefore, we infer that the north of Ankang Basin group is relatively old and the inconformity of coalescent time can explained by population’s combination. Similarly, the south of Ankang Basin group might be occurred the same event, and preserved some specific haplotypes, this is further proved that Ankang Basin might be the refuge in the glacial age.In the geometric morphology aspects, we choose Oxya intricata(Stal.) populations from Qinling-Dabashan Mountains as our material, focus on the male epiproct of196individuals in13populations for geometric morphologic analysis. We choose12landmarks on the epiproct strictly and standardize the data, and had a study on ANOVA, MANOVA Tukey’s HSD test, CVA, thin-plate splines distortion figure and clustering analysis. This study aims to discuss whether the epiproct of Orthoptera insects is effective to discriminate intraspecies population, and whether the epiproct, as a mating-related structure, have any relationship with different environment. The results are listed as follow:1. The ANOVA analysis of centriod value indicated that there is significant size difference between Oxya intricata(Stsl.) populations (F=8.6710, p=0.0000), and the pairwise comparison of Tukey’s HSD test also shown a significant difference between populations.2. CVA showed a significant shape difference among Oxya intricata populations. CV1and CV2explain the most part of shape variable (63.83%). In the scatter plot,13populations in Qinling-Dabashan Mountains were separated apparently in the Cartesian coordinates. According to the shape distortion figure, we could visually observe the main difference position and variational direction of epiproct.3. The clustering analysis combining geographical distribution could divide the13Oxya intricata(Stal.) populations into3groups:the south slope of Qining Mountain group, the Hanjiang River Basin group and the north of Daba Mountain group. This indicated that the shape trait of epiproct could apply as an evidence for the identification of intraspecies. The shape variation also might be limited by the environment factor, which is influence the reproduction of populations.4. By means of selecting proper trait and the main variable position, geometric morphologic analysis could discriminate populations effectively based on the shape difference. Meanwhile, the results of geometric morphological analysis obtained from this study were able to support each other. Above all, the phylogeography relationship of Oxya intricata(Stal.) population in Qinling-Dabashan Mountains is insignificant because of the frequent geneflow, but the genetic differentiation between geographical groups is obvious, and influence by the two aspects of geographical distance and vicariance. Under the impact of glacial period, population had occurred expansion several times, and Ankang Basin area might be the refuge. The male Oxya intricata(Stal.) epiproct shape difference is correlated with geographical environment. To combine population genetic result and geometric morphological analysis, we found that there is no significant relationship of Oxya intricata(Stal.) in Qinling-Dabashan Mountain between population genetic and shape variation. |
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