| Hynobius amjiensis belongs to the Amphibian,Caudata,Hynobiidae,Hynobius.It only distributed in three very narrow distribution areas,which are located in Zhejiang Hynobius amjiensis National Nature Reserve,Zhejiang Qingliang Peak National Nature Reserve,and Anhui Qingliang Peak National Nature Reserve.H.amjiensis is endemic to our country and one of the First-Grade State Protection animal in China.Due to the sparse population,the low survival rate,the continuous reduction of habitat area and quality,it was listed as a critically endangered species(CR)in the International Union for Conservation of Nature(IUCN)Red List of Threatened Species.In order to better adopt scientific and effective strategies to conserve the existing populations of H.amjiensis,in this study,75 individuals,which was from three populations(LWS,ZJQLF and AHQLF),was been studied by Double Digest Restriction-site Associated DNA(dd RAD)sequencing.Based on the high-quality single nucleotide polymorphism(SNP)site,the population genetic diversity,population structure of H.amjiensis was been understanded.Which will guide the formulation and implementation of the conservatiom policy on H.amjiensis.After rawdatas with the low quality were filtered and 8 individuals with low depth were removed,a total of 194.04G of the effective data was obtained after quality control,with an average of 2.94G per sample.A total of 1,236,879 SNP loci shared by at least 80%of individuals were called after mapped.Via genetic diversity analysis based the high quality SNPs,the results of heterozygosity(Ho,He)and nucleotide polymorphism(Pi)analysis of each population showed that among the three populations,the genetic diversity of the ZJQLF population was the highest(He=0.20028,Pi=0.22632),and the genetic diversity of the AHQLF population was the lowest(He=0.16657,Pi=0.16852).Regarding the genetic structure of the three populations of H.amjiensis,the phylogenetic tree and PCA results showed that there was obvious clustering among the three populations,Admixture divided the three populations into three subgroups,which was consistent with the results of genetic distance.In addition,the genetic relationship between ZJQLF and AHQLF is closer,but it has also begun to differentiate.The gene flow analysis results showed that there was no significant gene flow between the three populations.Demography history results showed that during the Pleistocene,every population had population expansion,but even so,the effective population size of every population did not exceed 1,200 between 10~5years ago-10~4 years ago.Based on this research,the following protection suggestions can be put forward:(1)From the perspective of genetic diversity,in order to increase the survival rate of the AHQLF population of H.amjiensis,it is necessary to carry out targeted artificial breeding work,at the same time,it can be combined with the introduction to increase the survival rate of the AHQLF population.(2)From the perspective of inbreeding of H.amjiensis,the inbreeding phenomenon of ZJQLF population is particularly serious.Therefore,in addition to artificial breeding,reasonable man-made migration should be used to promote gene exchange with other populations,thereby increasing the genetic diversity within the population.(3)According to the existing population structure,all three populations can be used as separate management units for protection.(4)At the same time,it is recommended to establish an ecological corridor between the two distribution areas in Qingliang Peak to reduce human interference,and provide conditions for gene exchange between natural populations as much as possible,so as to increase the genetic diversity of the two populations of Qingliangfeng.So,the success of this research will provide valuable reference for the development of high-throughput SNPs genetic markers and conservation genomics research of H.amjiensis and even Hynobius. |
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