| Hemiculter leucisculus belongs to the order Cypriniformes,Cyprinidae,Hemiculter Bleeker.It is widely distributed and mainly lives in the upper and middle layers of rivers and lakes.Because of its delicious meat,it was often overfished.Especially,the source area of the Huaihe River is a densely populated zone.Hemiculter leucisculus was one of the main fishing targets for fishermen,and its resources were constantly decreasing.In addition to the frequent construction of reservoirs and other water conservancy projects in the Huaihe River Basin,the habitat fragmentation have affected the gene flow of fish,resulting in the decline of fish germplasm in the Huaihe River Basin of Henan Province.In order to study the current status and conservation strategies of fish germplasm resources in the source area of Huaihe River in Henan Province,a wide range of H.leucisculus was studied.Using nuclear gene RAG2 and mitochondrial gene Cytb and COI gene fragments as molecular markers,To study the genetic diversity of the eucalyptus population in the source region of the Huaihe River,analyze the genetic structure of the H.leucisculus population,and combine with the geological history of the Huaihe source region to discuss the historical dynamics of the H.leucisculus population and to elucidate the changes in the genetic diversity of the H.leucisculus in the source region of the Huaihe River in Henan Province.Revealing its key protected areas provide theoretical basis for the conservation and rational development of H.leucisculus and other fish resources in the source area of the Huaihe River.The main results are as follows: 1.Genetic diversity of H.leucisculus in the Huaihe River Source RegionAnalysis of genetic diversity Based on Nuclear Gene RAG2 showed that the average haplotype diversity(h)of 10 populations were 0.940 ± 0.011,The average nucleotide diversity(?)was 0.00246 ± 0.00057.The GH population had the lowest haplotype diversity and nucleotide diversity(h = 0.645 ± 0.106,? = 0.00090 ± 0.00013),The GDX population had the highest haplotype diversity(h = 1.000 ± 0.063);Analysis of genetic diversity based on the Cytb gene showed that the average haplotype diversity(h)of 10 populations was 0.915 ± 0.011,the average nucleotide diversity(?)was 0.00461 ± 0.00060.The haplotype diversity and nucleotide diversity of XHH population were both the lowest(h = 0.509 ± 0.101,? = 0.00229 ± 0.00045).The PPH population had the highest haplotype diversity(h = 0.833 ± 0.069),while the JQH population had the highest nucleotide diversity(? = 0.00400 ± 0.00034);Analysis of genetic diversity based on COI gene showed that the average haplotype diversity(h)of 10 populations was 0.761 ± 0.021,the average nucleotide diversity(?)was 0.00307 ± 0.00070.The haplotype diversity and nucleotide diversity of XHH population were both the lowest(h = 0.462 ± 0.110,? = 0.00147 ± 0.00035),TJH population had the highest haplotype diversity(h = 0.807 ± 0.047),while the NW population had the highest nucleotide diversity(? = 0.00342 ± 0.00026).Combining with nuclear gene and mitochondrial gene,it was concluded that the population of H.leucisculus in the source area of Huaihe River presents high haplotype diversity and low nucleotide diversity.The genetic distance between populations is-0.06277 to 0.54589.2.Population genetic structure of the H.leucisculusAnalysis of the population genetic structure of the H.leucisculus,based on the nuclear gene RAG2,showed that the average genetic distance within the population was 0.00464,the genetic distance between populations was-0.10850~0.60635,There was a significant difference between the WQ population with other populations(p<0.001),The range of genetic differentiation index varies from 0.34419 to 0.51300.AMOVA showed that The the intra-group genetic variation accounted for 24.64%(p<0.001).According to different rivers,10 Hemiculter leucisculus populations were divided into 4 groups for multi-level AMOVA analysis,The genetic variation among the populations of different water lines in the source area of the Huaihe River was 0.09%(p>0.05),genetic variation mainly comes from within the population.The Cytb gene showed an average genetic distance of 0.00247 within the H.leucisculus populations.The COI gene showed an average genetic distance of 0.00585 within the H.leucisculus population.The genetic distance between populations varied from-0.06844 to 0.55539,Cytb and COI genes showed that the genetic differentiation between LDK population and other populations were larger,The genetic differentiation index between LDK population and XHH population was 0.56282(p<0.0001).Analysis of AMOVA of 10 H.leucisculus Populations in the Source Region of Huaihe River Based on Cytb Genes,The genetic variation among groups within the group accounted for 26.14% of the total genetic variation(p<0.001),COI results are much smaller than Cytb,The genetic variation among groups within the group accounted for 9.35% of the total genetic variation(p<0.001).According to different water systems,10 H.leucisculus populations were divided into 4 groups for multi-level AMOVA analysis.The genetic variation among different groups of different water systems in the source area of the Huaihe River was 2.97%(p>0.05),The results of COI analysis showed that the genetic variation among groups was 3.47%(p>0.05).Neither is significant,Genetic variation mainly comes from within the population.Combined with the analysis of haplotype network,there was no obvious pedigree structure and geographical structure among the 10 H.leucisculus populations in the source area of the Huaihe River.3.Historical dynamic analysis of the H.leucisculusThe results of neutral test results and nucleotide mismatch of nuclear gene RAG2 indicated that the populations in the source region of the Huaihe River had undergone recent population expansion.Bayesian skyline point map(BSP)displayed a steady growth between 0.06 and 0.01 million years ago.The results of neutrality test and nucleotide mismatch maps of Cytb gene both indicated that there was no recent population expansion for the Hemiculter leucisculus population in the source region of the Huaihe River.BSP showed that the H.leucisculus had a steady growth between 0.009 and 0.005 million years ago.The effective population size growth quickly since 0.005 million years ago.Mitochondrial COI Gene Neutrality Test Results Are Inconsistent with Results of Nucleotide Mismatches,The results of the neutral test show that the D values and Fst values of the 10 geographical populations of H.leucisculus and the overall population of the Huai River source area are all positive.The P value is greater than 0.05,It shows that there has been no population expansion in this population recently.The distribution of the discrepancy shows a single peak,It indicates that the population has recently experienced population expansion.Bayesian skyline point map(BSP)display,The H.leucisculus is steady at 0.0025-0.02 million years,Between 0.0022 and 0.0012 million years of effective population growth trend,0.0012 million year-to-date effective population decline. |
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