【作者】 单磊；

【导师】 魏开建； 张桂蓉；

【作者基本信息】 华中农业大学 ， 水产养殖， 2009， 硕士

【摘要】 本研究利用12对微卫星引物对来自我国长江流域的夹江群体（JIA）、洞庭湖群体（YUE）、武汉群体（WUH）、鄱阳湖群体（XIN）、太湖群体（WUX）以及淮河下流的灌南群体（GUA）等6个二倍体泥鳅野生群体进行了遗传多样性分析。首先对采集来的6个群体共计291尾泥鳅个体进行倍性检测,结果显示:洞庭湖群体和武汉群体中分别有40尾和38尾泥鳅是四倍体（2n=100）,其余213尾为二倍体（2n=50）。其中二倍体泥鳅用于遗传多样性和遗传结构分析,结果表明:1.12个微卫星位点在这6个泥鳅群体中共检测到64个等位基因,平均每个位点5.33个,数目最多的位点是Mac425,为11个,最少的位点是Mac576和Mac627,均为2个。每个位点的等位基因在不同群体中的分布规律不同。2.Hardy-Weinberg平衡检验结果显示:6个泥鳅群体整体上在4个微卫星位点（Mac49、Mac229、Mac425和Mac456）偏离Hardy-Weinberg平衡,各泥鳅群体整体上均偏离Hardy-Weinberg平衡。3.12个微卫星位点在6个泥鳅群体中的平均多态信息含量（PIC）在0.052～0.757之间,平均观察杂合度（H_O）在0.050～0.968之间,平均期望杂合（H_E）在0.056～0.791之间。6个泥鳅群体的平均PIC为0.192～0.465,平均H_O为0.333～0.517,平均H_E在0.240～0.501之间。6个泥鳅群体的遗传多样性处于中等水平,其中以洞庭湖群体的遗传多样性最高,鄱阳湖群体、灌南群体次之,而夹江群体的遗传多样性最低。4.6个群体在各位点上的平均F_ST值为0.228。群体间的遗传分化系数G_ST为0.185,群体遗传变异的22.85%来自群体之间的变异（P＜0.001）,表明6个群体间存在高度遗传分化。5.长江上游夹江群体与长江中下游以及淮河下游群体间成对固定指数F_ST（0.282～0.399＞0.25）较大,基因流（N_m）较小（0.376～0.637＜1）,表明存在高度遗传分化;长江中下游的四个群体间F_ST（0.093～0.195）和N_m（1.000～2.431）处于中等水平,说明存在中度遗传分化;淮河下游的灌南群体与长江流域的太湖群体间F_ST（0.020）最小,N_m最大（12.021）,表明它们间的遗传分化最小。6.6个泥鳅群体间Nei’s遗传相似度（I）为0.707～0.979,遗传距离（D）为0.021～0.346。夹江群体和太湖群体间遗传距离最大（0.346）,灌南群体和太湖群体间遗传距离最小（0.021）。根据遗传距离构建的UPGMA和N-J系统树将这6个泥鳅群体分为2支:灌南群体、太湖群体、鄱阳湖群体、洞庭湖群体和武汉群体5个群体聚为一支,夹江群体单独聚为一支。其中,鄱阳湖群体和洞庭湖群体聚为一个亚支,灌南群体、太湖群体以及武汉群体聚成另一个亚支。更多还原

【Abstract】 Twelve microsatellite markers from loach（Misgurnus anguillicaudatus） were used to investigate genetic diversity among five diploid loach natural populations originating from the Yangtze River Basin（JIA,YUE,WUH,XIN,WUX） and one from Huai River Basin（GUA）.The ploidy of each specimen was determined by relative DNA content of erythrocytes based on flow cytometric analysis,and revealed that 40 individuals from YUE and 38 individuals from WUH were tetraploid,the other 213 specimens were diploid which were used for microsatellite DNA analysis.The results were as follows:1.64 alleles were tested at the 12 microsatellite loci in six loach populations and the mean allelic number per locus was 5.33.The most was 11 at locus Mac425,the least was 2 at loci Mac576 and Mac627.2.The Hardy-Weinberg equilibrium analysis revealed that genetic disequilibrium was observed at four loci（Mac49、Mac229、Mac425 and Mac456） across six loach populations and in each population across 12 loci.3.Average Polymorphic Information Content（PIC） at 12 loci across six populations was between 0.052 and 0.757,average observed heterozygosity and average expected heterozygosity ranged from 0.050 to 0.968 and from 0.056 to 0.791,respectively.For six loach populations at all loci,Average Polymorphic Information Content,average observed heterozygosity and average expected heterozygosity ranged from 0.192 to 0.465,from 0.333 to 0.517 and from 0.240 to 0.501,respectively.It indicated that there were moderate genetic variability among the six loach populations.The highest genetic variability was found in YUE population,and the lowest was in JIA population.4.The F-statistic analysis indicated that the total F_IS value at twelve microsatellite loci across six loach populations was -0.095,the total F_IT value was 0.154 and the total F_ST value（the fixation indices of subpopulation relative to the total population） was 0.228. The F_ST value revealed that the six loach populations were at a moderate genetic differentiation level.The total coefficient of differentiation(G_ST) was 0.185,indicated that only 18.5%of the total genetic diversity was partitioned among populations and 81.5% was within populations,which was supported by results of Analysis of Molecular Variance（AMOVA）.5.The pair-wise fixation index F_ST value and number of migrants N_m value between JIA and the other five populations respectively ranged from 0.282 to 0.399 and from 0.376 to 0.637,which showed that the genetic variance between JIA and the other five populations was at high level;the value of pair-wise F_ST and N_m between YUE,WUH, XIN and WUX populations was respectively ranged from 0.093 to 0.195 and from 1.000 to 2.431,which indicated that the genetic difference between the four populations was at moderate level;the maximum values of F_ST and N_m were observed between WUX and GUA populations,which meant that the genetic variance between them was at low level. All the values of pair-wise F_ST were at significant level. 6.The Nei’s standard genetic distance（D） among populations ranged from 0.021 to 0.346,the maximum occurred between JIA and WUX populations,and the minimum occurred between GUA and WUX populations.The cluster analysis showed that the six loach populations were clustered into two branches.WUX and GUA populations were clustered into one sub-branch at first and WUH population joined them later,YUE and XIN populatins were clustered into another sub-branch,the two sub-branches grouped a branch.Finally,JIA population grouped a branch alone.The present research on the genetic diversity of diploid loach natural populations provide some important information for natural resources conservation and genetic breeding of M.anguillicaudatus.更多还原