Study On Morphology And Genetic Variation Of Apodemus Agrarius Populations On Islands And Continent

Island habitats differ significantly from the continental environment in many ways due to their geographical isolation,simple biological groups,and unique historical causes.Apodemus agrarius,belongs to Rodentia,Muridae,Apodemus,and widely distributed in the north and south of China.In this study,the morphology and genetic variation of the Apodemus agrarius population which distributed in Zhoushan Archipelago and continent were studied.First,the sample line method was used to collect samples of Apodemus agrarius on 6 islands(Dazhairuoshan Island,Cishan Island,Damao Island,Xiaopanzhi Island,Taohua Island,Liuheng Island)of Zhoushan Archipelago and inland areas(Yiwu,Jinhua),and the comparative analysis was carried out on several indicators of their morphology.Second,using microsatellite(SSR)molecular marker technology to study the level of genetic diversity,the sources of variation and the level of genetic differentiation in the 6 island populations and between island population and continental population of Apodemus agrarius.Also explored the impact of island size and isolation on population genetic variation.Finally,studied the diffusion situation between the island populations of Apodemus agrarius and between island population and continental population.Based on the above research,the main conclusions are as follows:1.By comparing the morphological indicators such as the average body length,average weight,and average tail length of 7 Apodemus agrarius geographical populations,the coefficient of difference between the geographical populations of each pair was obtained.According to the difference coefficient,the differences in the morphology indicators of 7 Apodemus agrarius geographical populations is small.Only Apodemus agrarius on the continental population and the Cishan population showed differences in subspecies levels under carcass weight and hind foot length,and the morphological differences between other geographic populations have not reached the level of subspecies.The morphological differences between the island population and the continental population also have not reached the level of subspecies.The cluster analysis of 7 geographic populations based on morphological indicators showed that Taohua population,Liuheng population,Xiaopanzhi population and the continental population were clustered into one group.Among them,Taohua population,Liuheng population,Xiaopanzhi population are relatively close,but the continental population is relatively far away.Dazhairuoshan population,Damao population,and Cishan population were clustered into another group,and among them,Dazhairuoshan population and Damao population are relatively close,but Cishan population is relatively far away.The results of single factor analysis of variance show that there are small differences between the Apodemus agrarius geographical populations.Among them,based on the analysis of weight,carcass weight,hind foot length and ear length,it can be seen that Cishan population shows a large difference from other geographical populations.The results of principal component analysis also showed that Cishan population was relatively different from other populations.2.Based on 14 pairs of microsatellite molecular markers,the nuclear genes of 7 Apodemus agrarius geographical populations were analyzed.It was found that the average number of alleles was 8.2188(3.8889?18.2857),the average effective number of alleles was 4.9703(3.0091?11.3503),the average observed heterozygosity was 0.5480(0.4389?0.6926),the average expected heterozygosity was 0.7433(0.6170?0.9198),and the average polymorphic information content was 0.6518(0.3528?0.8957),which reflected high genetic diversity within the species.Among these populations,the genetic diversity of the continental population is the highest,the genetic diversity of Liuheng population and Taohua population is high,while the genetic diversity of Cishan population and Xiaopanzhi population is low.The average genetic differentiation coefficient among 7 geographical populations is 0.2655(0.1139?0.5137),which is at the ultra-high level.The genetic variation within the population accounted for 80.29%,while the genetic variation between the different geographical populations accounted for 19.71%.It shows that the nuclear gene variation of the Apodemus agrarius geographical populations was mainly derived within the populations.The observed heterozygosity is 0.5185,the expected heterozygosity is 0.8713,the polymorphic information content is 0.8546 of the island population,while the observed heterozygosity is 0.5663,the expected heterozygosity is 0.9198,the polymorphic information content is 0.8957 of the continental population.From the point of view of heterozygosity and polymorphic information content,the continental population is higher than the island population.Therefore,the genetic diversity of the continental population is higher than that of the island population of Apodemus agrarius.The genetic differentiation coefficient between the continental population and the island population is 0.0629,indicating that there is a moderate degree of differentiation between the continental population and the island population of Apodemus agrarius.The genetic variation within the population accounted for 93.71%,while the genetic variation between the continental population and the island population accounted for 6.29%,so the variation of nuclear gene of Apodemus agrarius was mainly derived within the populations.3.Based on the microsatellite markers,the diffusion research on the Apodemus agrarius showed that Apodemus agrarius did not spread between the islands of Zhoushan Archipelago or between the islands and the continent.