| Amphibians are the group of vertebrates with aquatic to terrestrial transition.Due to the characteristics of life history,their life activities are highly dependent on the stability of the environment,especially vulnerable to habitat loss and fragmentation.Under the background of global warming and global population decline of amphibians,it is necessary to explore the genetic diversity and genetic structure of different geographical populations of amphibians to better protect their genetic resources.Bufo andrewsi,as one of China's endemic toads,is widely distributed in Sichuan Province,Yunnan Province,Guizhou Province,Guangdong Province,Guangxi Zhuang Autonomous Region and other places in China.As a kind of gentle and holometabolous development amphibian,and highly dependent on the environment during reproduction and growth,B.andrewsi is a good model for research.In this paper,microsatellite marker and mitochondrial control region gene were used to detect and analyze the diversity of 20 populations in B.andrewsi,and evaluated the situation of ecological distribution.We isolated 12 polymorphic microsatellite loci by none denatured polyacrylamide gel electrophoresis(PAGE).A total of 627 individuals of B.andrewsi genotyping succeed.A total of 132 alleles were found in the 20 study populations,alleles ranged from 4 to 23 of per locus,with an average number of 11.We sequenced the mitochondrial control region of B.andrewsi,a total of 549 individuals mitochondrial D-loop region fragment was obtained with a length of 568 bp,which defined 94 haplotypes,just 26(27.66%)haplotypes were shared among populations,and 68 haplotypes belong to a particular population.A high level of genetic diversity and genetic differentiation among the populations of this specie,whether based on microsatellite data analysis or mitochondrial sequence analysis.The best clustering group of 20 geographic populations was 2(K = 2)form Structureanalysis based on microsatellite data.We constructed the phylogenetic tree of all haplotypes by Bayesian and maximum likelihood methods,and the topology of the trees was consistent.The populations of KE,QB,JMK,PTG and XGJ from Yunnan province,witch haplotypes were clustered into one branch,haplotypes from WL,GD,LMS,YCG,ZH were also clustered into one clade,and JZG population haplotypes were a single branch,however,there was no obvious clustering branch in other populations.And the results of haplotype network analysis showed similar results.Neutral test and mismatch distribution showed that all the 20 geographic populations did not undergo extensive expansion,and the populations were in a stable historical dynamics.Though simulated the niche of B.andrewsi by maximum entropy model(MAXENT),we found that places contained the highest richness of species were not only in the sampling dense areas,where there was no sampling,also had a higher abundance,which indicated that the species had a strong ability to survive.Nevertheless,in our study populations,the high positive Fis in 16 populations might be caused inbreeding.We should give enough attention to it,since inbreeding may cause a sharp decline in the number of populations,and which is a severe threat to the persistence of populations.Additionally,the bottlenecks in some populations caused by human hunting and the habitat destruction suggest that we should pay attention to the limited resources for amphibians' existence. |
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