| Based on the combined genes of mitochondrial Cytb and COI,this paper constructs existing fish phylogenetic trees in the Basin,studies the phylogenetic diversity of different communities,and finds the correlation between the phylogenetic diversity index and environmental factors such as water temperature and water depth.In addition,4 Cyprinidae fish species were selected for analysis of genetic diversity and population history dynamics,investigating their population genetic structure.The main results are as follows1.Based on the combined gene sequences,152 fish sequences in Baiyangdian Basin were analyzed for α diversity and phylogenetic diversity.The results showed that:the haplotype phylogenetic tree of 54 species of fish in Baiyangdian Basin could be divided into three branches,branch I was Cypriniformes,Branch Ⅱ was Siluriformes,and Branch III included Perciformes,Osmeriformes,Synbranchiformes,and Beloniformes.According to the study of community diversity by phylogenetic tree,the α diversity index was ranked as Juma River Community>Baiyangdian Community>Sha River Community>Wangkuai Community>Fu River Community>Xiaoyi River Community>Xidayang community.In the phylogenetic diversity indices,the results showed that the phylogenetic diversity(PD)ranking was:Baiyangdian Community>Juma River Community>Wangkuai Community>Sha River Community>Fu River Community>Xiaoyi River Community>Xidayang community,PD and MNTD were significantly correlated,NTI and NRI were not correlated,and species richness was significantly correlated with PD.The results show that NTI decreases with the increase of average water temperature,showing significant correlation2.Based on the combined gene sequences,the genetic structure and historical dynamics of the populations of Zacco platypus in the Sha River and Juma River of the Baiyangdian Basin were analyzed.The results showed that there were a total of 141 samples from the two populations,and 45 haplotypes were detected,of which 2 were shared haplotypes.The genetic diversity of the Juma River population were higher than the Sha River population(h:0.7120>0.4514,π:0.01182>0.00313)The phylogenetic tree,haplotype network and genetic differentiation coefficient(FST)all showed that there was no obvious differentiation between the two populations.Neutral test and mismatch analysis show that the Sha River population has not experienced population expansion.Combined with the Bayesian skyline plot and Mismatch distribution,it shows that the Juma River population experienced population expansion 0.004 million years ago.Combined with the haplotype network diagram and phylogenetic tree analysis,the Shahe population may have experienced the founder effect and spread from the Jumahe population.With reference to the evolution rate of the Cytb gene of carps from 0.84%to 1%per million years,the divergence time of the two populations is estimated to be 0.089 to 0.067 million years ago3.Based on the combined gene sequences,the genetic structure and population historical dynamics of Hemicculter leuciclus populations distributed in 5 water areas of Baiyangdian Basin,namely Baiyangdian,Sha River(including Wangkuai Reservoir),Fu River,Xiaoyi River,and Tang River(including Xidayang Reservoir)were analyzed.The results showed that there were a total of 155 samples from 5 populations,and 45 haplotypes were detected,of which 8 were shared haplotypes.The genetic diversity of Baiyangdian population,Sha River population,and Xiaoyi River population(h:0.8479～0.9447,π:0.00727～0.01081)was higher than that of Tang River population and Fu River population(h:0.7190～0.7596,π:0.00533～0.00621).Phylogenetic tree,haplotype network and genetic differentiation coefficient(FST)showed that there was no obvious differentiation among the five populations Neutral test,mismatch analysis and Bayesian skyline plot show that the Xiaoyi River population experienced a population expansion event 0.075 million years ago,and then showed a downward trend,while other populations showed a decreasing trend of effective population after remaining stable.It was estimated that the divergence time of five populations was 0.288～0.129 million years ago4.Based on the combined gene sequences,the genetic structure and population history dynamics of Rhynchocypris lagowskii populations distributed in Juma River and Tianjin Ju River were analyzed.The results showed that there were 71 samples from the 2 populations,26 haplotypes were detected,of which 1 shared haplotype.The genetic diversity of the Ju River population was higher than that of the Juma River population(h:0.8603>0.7338,π:0.01311>0.00310).The phylogenetic tree,haplotype network and genetic differentiation coefficient(FST)indicate that there was no obvious differentiation between the two populations.Neutral test and Bayesian skyline plot show that the Juma River population experienced a population expansion event 0.045 million years ago,and the Ju River population remained stable.Combining with the haplotype network and phylogenetic tree analysis,the Juma River population may have experienced the founder effect,which was derived from the diffusion of the Ju River population.The divergence time between the two populations is estimated to be 2.077～1.578 million years ago5.Based on the combined gene sequences,the genetic structure and population history dynamics of the Microphysogobio hsinglungshanensis populations distributed in Juma River and Sha River were analyzed.The results showed that there were 76 samples in the two populations,27 haplotypes were detected,4 of which were shared haplotypes.The genetic diversity of the Sha River population was higher than that of the Jumahe population(h 0.8954>0.8329,π:0.00606>0.00480).Phylogenetic tree,haplotype network and genetic differentiation coefficient(FST)all indicate that there is no differentiation among populations The mismatch distribution and Bayesian skyline plot show that the Juma River population experienced population expansion event 0.25 million years ago,and the estimated time of divergence between the two populations was 0.138～0.105 million years ago. |
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