濒危植物翅果油树种群的遗传多样性和遗传分化研究

利用微卫星（SSR）标记对来自山西和陕西两省的7个翅果油树（Elaeagnus mollisDiels）种群进行遗传多样性和遗传结构研究。10对SSR标记共检测到126个位点,其中多态位点114个。在物种水平上,平均多态位点百分率为90.79%,有效等位基因数（Ne）、Nei基因多样性指数（H）和Shannon多样性指数（I）分别为1.6072、0.3166、0.4603;在种群水平上,多态位点百分率为61.99%,有效等位基因数（Ne）、Nei’s基因多样性指数（H）、Shannon多样性指数（I）分别为1.5445、0.2683、0.3815。遗传分化系数GST为0.2074,表明了翅果油树种群的遗传变异主要存在于种群内。基因流Nm为1.9111〉1,说明种群间基因交流可以阻止由于遗传漂变导致的遗传分化。聚类结果表明,翅果油树种群间的遗传距离与地理距离有一定的相关性,经Mantel检验,种群的地理距离与遗传距离之间呈正相关,但未达到显著水平（p〉0.05）。结果表明,遗传多样性水平与物种本身特性和不同干扰生境有关,濒危植物并不一定表现为遗传变异水平的降低。     

Analysis of genetic variability and population structure of the endemic medicinal Limonium sinense using molecular markers

Limonium sinense is an endemic medicinal herb used to treat fever, hemorrhage and other disorders. In the present study, population genetic diversity was elucidated using random amplified polymorphic DNA (RAPD), inter simple sequence repeat (ISSR) and amplified fragment length polymorphism (AFLP) primers. Percentage of polymorphic bands, Nei's gene diversity and Shannon's information index revealed a high level of genetic diversity at species level. The analysis of molecular variance revealed that 69.88% (RAPD), 71.19% (ISSR) and 70.97% (AFLP) of variability were partitioned among individuals within populations, which indicated the coherent trend by Gst (0.3849/0.3577/0.3670). Gene flow number (Nm) was 0.581/0.618/0.612, which indicated that there was a limited gene exchange between populations. The UPGMA clustering results showed that the genetic distance had no significant correlation with geographic distance. These results indicate that these markers were reliable tools for the differentiation and determination of the genetic diversity among the populations of L. sinense and the conservation of existing natural population is necessary.     

Invaded range of the blackberry pathogen Phragmidium violaceum in the Pacific Northwest of the USA and the search for its provenance

Field surveys in 2006 confirmed that the exotic rust fungus Phragmidium violaceum was widespread on Rubus armeniacus and Rubus laciniatus in the Pacific Northwest of the USA. The origin and dispersal pattern of this obligate biotrophic pathogen in the USA were investigated by comparing the genetic diversity and structure of 27 isolates each from the USA and Europe, and 20 isolates from Australia where an invasion occurred in 1984. Analysis of 11 microsatellite loci revealed 74 unique genotypes, with the European population having a significantly higher level of allelic diversity and number of private alleles compared to populations from the USA and Australia. Principal coordinate analysis (PCA), analysis of molecular variance and pairwise comparisons of Φ confirmed a strong level of differentiation among continental populations, with little divergence between isolates from the USA and Europe, but a high level of differentiation between these isolates and those from Australia. These results were broadly supported by the Bayesian cluster analysis, which indicated that at K = 3 the clustering of the isolates corresponds to their geographic origin. Bayesian clustering, PCA as well as insignificant migration estimates from Europe to the USA suggest that the USA population is not a direct descendant from the European P. violaceum population. There was a weak association between genetic and geographic distance among the USA isolates, suggesting invasion was initially localized prior to dispersal or that the population may have been present for some time prior to first detection in 2005.     

AFLP analysis of genetic diversity of the endangered species Sinopodophyllum hexandrum in the Tibetan region of Sichuan Province, China

Amplified fragment length polymorphism (AFLP) markers were used to estimate the genetic diversity of seven wild populations of Sinopodophyllum hexandrum (Royle) Ying from the Tibetan region of Sichuan Province, China. Six primer combinations generated a total of 428 discernible DNA fragments, of which 111 were polymorphic. The percentage of polymorphic bands (PPB) was 25.93 at the species level, and PPB within population ranged from 4.91 to 12.38%. Genetic diversity (H(E)) within populations varied from 0.01 to 0.04, averaging 0.05 at the species level. As revealed by the results of AMOVA analysis, 58.8% of the genetic differentiation occurred between populations, and 41.2% within populations. The genetic differentiation was, perhaps, due to the limited gene flow (Nm = 0.43) of the species. The correlation coefficient (r) between genetic and geographical distance using Mantel's test for all populations was 0.698 (P = 0.014). The UPGMA cluster analysis revealed a similar result in that the genetic distances among the populations show, to a certain extent, a spatial pattern corresponding to their geographic locations. On the basis of the genetic and ecological information, we propose some appropriate strategies for conserving the endangered S. hexandrum in this region.     

Genetic diversity and structure of Cordyceps sinensis populations from extensive geographical regions in China as revealed by inter-simple sequence repeat markers

Cordyceps sinensis is one of the most valuable medicinal caterpillar fungi native to China. However, its productivity is extremely limited and the species is becoming endangered. The genetic diversity of eighteen C. sinensis populations across its major distributing regions in China was evaluated by inter-simple sequence repeat (ISSR) markers. A total of 141 markers were produced in 180 individuals from the 18 populations, of which 99.3% were polymorphic. The low average of Shannon (0.104) and Nei index (0.07) of the 18 populations indicates that there are little genetic variations within populations. For all 18 populations, estimates of total gene diversity (H_T), gene diversity within populations (H_S), coefficient of genetic differentiation (G_ST), and gene flow (Nm) were 0.170, 0.071, 0.583, and 0.357, respectively. This pattern suggests that the genetic diversity of C. sinensis is low and most of the ISSR variations are found among populations with little gene exchange. The 18 populations are divided into five groups based on the genetic distance and the grouping pattern matches with the geographic distribution along the latitudinal gradient. The five groups show obvious difference in the G_ST and Nm values. Therefore, the genetic diversification of C. sinensis populations may be determined by geographic isolation and the combined effects of life history characters and the interaction with host insect species. The information illustrated by this study is useful for selecting in situ conservation sites of C. sinensis.     

麦无网长管蚜不同地理种群遗传多样性的ISSR标记研究

为阐明麦无网长管蚜Metopolophium dirhodumus不同地理种群的遗传多样性,利用ISSR分子标记对6个地区（河北保定、定州、石家庄、邢台、邯郸,山东聊城）的麦无网长管蚜种群进行了遗传多样性研究。23条ISSR引物扩增出了297条清晰条带,其中172条（57.91%）具有多态性。遗传多样性分析结果表明：麦无网长管蚜群体间的遗传多样性（57.91%）高于群体内的遗传多样性（26.24%）,其中河北保定种群和河北邯郸种群的种群内遗传变异最小（24.92%）,河北石家庄种群的种群变异最大（41.75%）,河北和山东地区的种群（除河北石家庄）之间没有显著遗传差异。根据种群变异来源分析,有26.44%遗传变异来源于种群间,73.56%变异来自于种群内（Gst=0.2644）,不同地理种群间并没有出现分化现象（Nm=1.3910）。利用不加权算术平均法（UPGMA）对6个种群进行统计分析,构建进化树,发现6个种群分为了两大类,而其地理距离与遗传距离并不存在相关性,地理空间并未对其种群间的基因交流产生影响。麦无网长管蚜有较高的遗传多样性,而各个种群间并没有明显遗传分化的趋势。本研究有关麦无网长管蚜不同地理种群基因流和遗传变异将为控制麦蚜危害和田间综合防治提供必要的数据支持。     

基于线粒体COI基因序列的大豆食心虫中国东北地理种群遗传多样性分析

【目的】大豆食心虫Leguminivora glycinivorella (Matsumura)是一种危害大豆的主要害虫,在中国北方地区危害较重。本研究旨在探讨大豆食心虫在中国东北不同地理种群间的遗传变异。【方法】测定了10个不同地理种群153个个体的线粒体细胞色素氧化酶亚基Ⅰ (mtCOI)基因的657 bp序列,利用DnaSP 5. 0和Arlequin 3. 5. 1. 2等软件对大豆食心虫种群间的遗传多样性、基因流水平和分子变异进行分析。【结果】结果表明：10个地理种群间的COI基因共有36个变异位点和17个单倍型,其中1个单倍型为10个种群所共享。总种群的单倍型多样性指数Hd为0.456,各地理种群单倍型多样度范围在0~0.634之间。总群体的固定系数Fst为0.12545,遗传分化系数Gst为0.06326,总基因流Nm为3.49,且各种群间的基因流均大于1,种群间基因交流的水平较高。【结论】大豆食心虫种群内遗传多样性水平处于中低等水平。总群体和各种群的Tajima’s D检验结果皆不显著,说明中国东北地区大豆食心虫在较近的历史时期内没有出现种群扩张现象。AMOVA分子变异分析结果表明,大豆食心虫的遗传分化主要来自种群内部,而种群间未发生明显的遗传分化。各地理种群的单倍型在系统发育树上和中介网络图上散布在不同的分布群中,缺乏明显的地理分布格局。各种群的遗传距离与地理距离之间没有显著线性相关性,种群间的基因交流并未受到地理距离的影响。     

RAPD analysis of genetic diversity and population genetic structure of Stipa krylovii Reshov. in Inner Mongolia steppe

Random amplified polymorphic DNA (RAPD) analysis was used to characterize the genetic diversity and population genetic structure of Stipa krylovii populations in Inner Mongolia steppe of North China. Thirteen 10 bp oligonucleotide primers, which generated 237 RAPD bands, were used to analyze 90 plants of five populations from three regions, meadow steppe, typical steppe and desert steppe, from the east to the west. The genetic diversity of Stipa krylovii that was revealed by observed number of alleles (na), expected number of alleles (ne), Nei's diversity index (h), Shannon's diversity index (H), amplificated loci, polymorphic loci and the percentage of polymorphic loci (PPB) increased from the east to the west. The Pearson's correlation analysis between genetic diversity parameters and ecological parameters indicated that the genetic diversity of Stipa krylovii was associated with precipitation and cumulative temperature variations along the longitude (humidity were calculated by precipitation and cumulative temperature). Dendrogram based on Jaccard's genetic distance showed that the individuals from the same population formed a single sub-group. Although most variation (56.85%) was within populations, there was high genetic differentiation among populations of Stipa krylovii, high differentiation within and between regions by AMOVA analysis. Either Nei's unbiased genetic distance (G(ST)) or gene flow (Nm) among pairwise populations was not correlated with geographical distance by Mantel's test (P > 0.05), suggesting that there was no consistency with the isolation by distance model in these populations. Natural selection may have played a role in affecting the genetic diversity and population structure, but habitat destruction and degradation in northern grassland in China may be the main factor responsible for high genetic differentiation among populations, within and among regions.     

High levels of genetic polymorphism in the insular endemic herb Jepsonia malvifolia.

Jepsonia malvifolia is a long-lived perennial herb endemic to the Channel Islands of southern California and Guadalupe Island, Mexico. Twelve populations of J. malvifolia on San Clemente Island were surveyed for their genotype at 21 allozyme loci, revealing high levels of genetic polymorphism. For all individuals across San Clemente Island, 95.2% of loci are polymorphic with A(p) = 2.90 and H(e) = 0.179. Populations averaged 60.2% polymorphic loci with A(p) = 2.42 and H(e) = 0.158. Most variation is found within rather than among populations (G(ST) = 0.101), although differentiation among populations is significant. Genetic identities range from 0.936 to 0.999 with mean I = 0.975. There is no significant relationship between genetic and geographic distance. Gene flow among populations is Nm = 9.5 based on private alleles and Nm = 2.2 based on F(ST). Outcrossing rates based on fixation indices average t = 0.753, indicating a primarily outcrossed mating system. The genetic variation observed is unusually high for an insular endemic herb and indicates that J. malvifolia is unlikely to be endangered by genetic factors.     

Assessment of the domestication state of ackee (Blighia sapida K.D. Koenig) in Benin based on AFLP and microsatellite markers

Ackee (Blighia sapida) is a native multipurpose species important for the livelihoods of the rural populations in Benin. Trees are found in natural forests or are managed by farmers in different traditional agroforestry systems. Genetic variation at amplified fragment length polymorphism (AFLP) markers, four nuclear microsatellites (nSSRs) and one chloroplast microsatellite (cpSSR) were investigated in 279 individuals from six wild and eight cultivated populations from Benin. The AFLP data revealed moderate levels of diversity of ackee in Benin (mean diversity values are proportion of polymorphic loci = 52.8% and Nei??s gene diversity = 0.157, for 375 AFLP fragments). The mean diversity values based on nSSR-markers are expected heterozygosity = 0.286, allelic richness = 2.77. Genetic variation of wild and cultivated populations did not differ markedly. AMOVA revealed that only 7.3 and 5.2% of the variation was partitioned among populations for nSSR- and AFLP-markers, respectively. A Mantel test based on these both marker-types revealed significant correlations between population pairwise geographic distance and genetic differentiation. Differentiation among cultivated populations was higher than among wild populations. The only polymorphic chloroplast microsatellite marker (ccmp7) showed three haplotypes. Cultivated populations from northeastern Benin were fixed on one haplotype which was not observed elsewhere indicating a different origin of these populations possibly from neighboring Nigeria. Farmer-led domestication had an impact on the spatial distribution of genetic variation but did not result in significant losses of diversity within populations. Measures to conserve genetic resources of ackee in each of the three main bioclimatic zones in Benin are proposed.     

有性生殖对栗疫病菌群体结构的影响

采用RAPD方法对来源于栗疫病菌8个不同子囊壳的子囊孢子后代和无性生殖的对照群体各23个菌株进行了群体结构的比较。从RAPD随机引物中筛选出扩增多态性丰富的4条引物,共扩增出条带73条,多态性检测率为100%。研究结果表明,在8个子囊壳和无性生殖群体中的基因多样性,64.27%由群体内部引起,只有35.73%的多样性由群体之间的基因差异引起。各子囊壳群体间存在的基因流动很小(Nm=0.8994)。有性群体和无性群体之间的遗传距离为0.1389,基因流动值为3.4212,说明子囊壳群体和无性生殖群体之间存在一定的系统关系。分析表明栗疫病菌子囊孢子后代在自然界的传播对自然界的病菌的多样性起重要的作用。     

Estimates of Gene Flow among Populations, Geographic Races, and Species in the Ipomopsis Aggregata Complex

Interpopulational gene flow within a species can reduce population differentiation due to genetic drift, whereas genetic exchange among taxa can impede speciation. We used allozyme data to estimate gene flow within and among geographic races and species of perennial herbs in the Ipomopsis aggregata complex (Polemoniaceae). Estimates of interpopulational gene flow within taxa from two methods (F statistics and private alleles) were correlated with one another. Gene flow among populations within each geographic race (subspecies) of I. aggregata was relatively high (Nm greater than approximately 1.0). Gene flow was also high among populations of I. arizonica and among four northern populations of I. tenuituba. However, gene flow was low (Nm less than 1.0) for I. tenuituba when a population representing subsp. macrosiphon was included. This is consistent with previous findings that subsp. macrosiphon has had an independent origin and is reproductively, as well as geographically, isolated. A recently developed model, based on hierarchical F statistics, was employed to estimate genetic exchange among taxa. Gene flow estimates were generally high among races of I. aggregata (dNmrace greater than 1.0) but were low among subspecies of I. tenuituba (dNmrace less than 1.0). Consistent with morphological evidence, estimates of interspecific gene flow were moderate between I. aggregata and I. tenuituba, which hybridize in several areas. However, contrary to morphological evidence, we estimated relatively high levels of interspecific gene flow involving I. arizonica. Our results suggest that I. arizonica has hybridized with other species without the transfer of morphological traits.(ABSTRACT TRUNCATED AT 250 WORDS)     

A Comparative Assessment of Genetic Diversity among Differently-Aged Populations of Spartina alternif lora on Restored Versus Natural Wetlands

We collected naturally recolonizing Spartina alterniflora (smooth cord grass) from each of three restored sites and one undisturbed reference site in southwestern Louisiana to assess the impact of wetland restoration on genetic diversity. We used amplified fragment length polymorphisms (AFLPs) to produce 94 polymorphic genetic markers, which were used to characterize genetic diversity as average heterozygosity and the proportion of polymorphic loci

. Overall our findings indicate that restored populations of S. alterniflora maintain levels of genetic diversity comparable to natural populations, which should provide some measure of resistance against environmental disturbances. Diversity estimates were lowest for the natural reference site ( = 0.1059;

= 0.2763), whereas estimates for the three restored sites ranged from < H > = 0.1148 to 0.1256 and

= 0.3114 to 0.3202. All sites maintained sufficiently high diversity levels to suggest significant rates of outcrossing. Overall, genetic differentiation among populations was small (Weir and Cockerham's Θ = 0.0645), with the values from each pairwise comparison among the populations increasing with the geographic distance between sites (range = 0.0490–0.1101). These values indicate an average migration rate of 3.6 migrants, either pollen or seeds, per generation.     

Genetic structure of populations of the closely related species of Melanopsis (Gastropoda: Cerithiacea) in Israel

Population genetic structure in the species of Melanopsis were studied by means of cellulose acetate gel allozyme electrophoresis, on 26 Melanopsis populations from Israel: six of Melanopsis buccinoidea Olivier, 1801, eight of Melanopsis saulcyi Bourguignat, 1853, one of Melanopsis meiostoma Heller et Sivan, 2000 , 11 of Melanopsis costata Olivier, 1804, represented by two subspecies: M. costata costata Olivier, 1804 and M. costata jordanica Roth, 1839. 14 loci (nine polymorphic) were scorable: Aat, Alp, Est-1, Est-2, Gpi, Hbdh, Idh-1, Idh-2, Iddh, Mdh, Mdhp, Mpi, Pgdh, Pgm. Gametic disequilibrium was postulated. D-statistics was computed, indicating limited migration, not epistatic selection as the source of disequilibrium. Exact multilocus and multipopulation tests showed a statistically significant heterozygote deficit in 18 populations and seven polymorphic loci. Inbreeding, Wahlund's effect and codominant mode of selection were postulated as causing homozygote excess. Mantel test indicated a statistically significant association between the pairwise θ and geographic distance, and no association between Nm and the geographic distance. The mean gene flow estimates Nm, derived from either θ or private alleles technique, were consistent. Hierarchical F-statistics showed slight differences between the taxa. The process of speciation within the genus seems not yet completed.     

Genetic differentiation in endemic Lobularia (Brassicaceae) in the Canary Islands

Patterns of genetic diversity were examined in five endemic subspecies of the Lobularia canariensis complex from six of the Canary Islands. The taxa are interfertile, insect-pollinated outbreeders with wind dispersal. Electrophoretic analysis revealed a high level of genetic polymorphism at ten loci coding soluble enzymes, with a mean of 2.38 alleles per locus, 73.7 % polymorphic loci, and a mean heterozygosity of 0.279. Excesses of homozygotes, indicating inbreeding, were observed in small populations. The average total diversity was high, F.,=0.518. Among-population diversity, F_ST=0.318, contributed more to the total diversity than within-population diversity, F_IS=0.222. Little geographic or taxonomic patterning of the allozyme variation was observed. The mean genetic identitity for pairwise comparisons of the 19 populations was 0.76, with a range of 0.51–0.96 and c. 17 % of the comparisons below 0.67 and c. 8 % above 0.90. The results contrast with the many cases of high genetic identities reported for populations of endemic plants on oceanic islands. High levels of allozyme divergence suggest a relatively old origin of the L. canariensis complex and a long period of isolation of some of the populations.     

Allozyme variation in the endangered insular endemic Castilleja grisea

BACKGROUND AND AIMS: Genetic diversity in Castilleja grisea, an endangered, perennial herb endemic to San Clemente Island, California was investigated. Subsequent to the elimination of goats from the island in 1992, many populations of C. grisea have reappeared and have been increasing in size. METHODS: Nineteen populations were surveyed for their genotype at 19 allozyme loci. KEY RESULTS: At the taxon level, 57.9 % of loci are polymorphic with A(P) = 3.09 and H(E) = 0.137. Populations averaged 33.0 % polymorphic loci with A(P) = 2.43 and H(E) = 0.099. Most variation is found within rather than among populations (G(ST) = 0.128), although differentiation among populations is significant. Genetic identities range from I = 0.960 to I = 1.000 with mean I = 0.990. There is no significant relationship between genetic and geographic distance. Gene flow among populations is Nm = 2.50 based on private alleles and Nm = 1.70 based on F(ST). Outcrossing rates based on fixation indices average t = 1.01, indicating a primarily out-crossed mating system. CONCLUSIONS: The observed genetic variation is moderately high, unusually so for an insular endemic species, suggesting that C. grisea may not have lost substantial genetic variation during 150 years of overgrazing, and indicating that it is unlikely to be endangered by genetic factors.     

内蒙古中东部不同草原地带羊草种群遗传分化

运用 RAPD技术对内蒙古不同草原地带分布的 5个羊草种群 (共 10 0个个体 )的遗传多样性进行分析。 31个随机引物(10 nt)在 5个羊草种群中共检测到 4 96个扩增片断 ,其中多态性片断 4 89个 ,总的多态位点百分率达 98.6 %。利用 Nei指数和Shannon指数估算了 5个种群的遗传多样性 ,并计算种群相似系数和遗传距离运用 UPGMA法进行聚类分析。结果表明 :无论是种群内还是种群间 ,羊草均存在较高的遗传变异 ,大部分的遗传变异存在于种群内 (Nei指数和 Shannon指数估算结果分别为 85 .4 %和 72 .5 % ) ,只有少部分的遗传变异存在于种群间 ;不同种群的遗传多样性存在差异 ,各种群的遗传多样性与其所处的地理位置具有显著的相关性 ;5个种群的平均遗传距离为 0 .5 0 95 ,变异范围为 0 .4 6 84～ 0 .5 4 76 ;聚类分析结果显示地理距离较近的种群遗传距离较小 ,首先聚在一起 ,而地理距离较远的种群遗传距离较大 ,说明羊草种群间的遗传分化与地理距离存在一定相关性 ;但地理距离最近的两个种群并未最先聚集 ,说明羊草种群间的分化还与其生境的异质性有关     

Genetic variation and clonal diversity of Bromus ircutensis Kom. in the Otingdag sandy land detected by ISSR markers

Genetic variation and clonal diversity of nine populations of Bromus ircutensis Kom. from the Otingdag sandy land were investigated using Inter Simple Sequence Repeat (ISSR) markers. A total of 102 bands were amplified by using II ISSR primers chosen for the study. Among those 99% were polymorphic indicating high level of genetic variation at the species level with a mean genetic diversity (H) of 0.292 and Shannon information index (1) of 0.450. Percentage of polymorphic loci (PPL) of nine populations was 76.48% on average, which provides more evidence of considerable genetic variation at the population level. AMOVA analysis revealed that total genetic variation was higher within populations (87.06%) than between populations (12.94%), which is mainly the result of the extensive gene flow (Nm = 1.682) among B. ircutensis populations. UPGMA cluster analysis divided the nine populations into two groups. There was significant or moderate negative correlations between genetic diversity parameters (PPL, H, 1) and longitude or latitude. Mantel test also showed a significant correlation between geographical distance and genetic distance (r = 0.681, p = 0.002). Our findings indicated that distribution of B. ircutensis populations was influenced by geographical and ecological factors. Clonal diversity was also high with 108 individuals identified by 11 ISSR primers being all of different genets. Our results provide a molecular basis for sustainable management and conservation ofB. ircutensis in the study area.     

Genetic variation in wild sorghum (Sorghum bicolor ssp. verticilliflorum (L.) Moench) germplasm from Ethiopia assessed by random amplified polymorphic DNA (RAPD)

The extent and distribution of genetic variation in wild sorghum (Sorghum bicolor ssp. verticilliflorum (L.) Moench) collected from five different geographical regions in Ethiopia were analyzed using random amplified polymorphic DNA (RAPD) markers for 93 individuals representing 11 populations. Nine decamer primers generated a total of 83 polymorphic bands with 8-12 bands per primer and a mean of 9 bands across the 93 individuals. The amount of genetic variation among the populations (H = 0.37) and among the geographical region (H = 0.44) was low to moderate, despite the high degree of polymorphic bands per primer. Similarly, the mean genetic distance (0.08) among populations as well as among regions of origin (0.04) of the population was found to be low. The low genetic variation may be due to the reduced population size of the wild sorghum in Ethiopia because of habitat change. Partitioning of the genetic variation into between and within the population as well as between and within the regions of origin revealed that 75% and 88% of the variation was found within the populations and within the regions, respectively. Cluster analysis of genetic distance estimates further confirmed low level of differentiation of wild sorghum populations both on population and regional bases. The implications of the results for genetic conservation purposes are discussed.     

长江中下游不同地理种群鳜遗传结构研究

以长江、通江湖泊(洞庭湖、鄱阳湖)、陆封型湖泊(牛山湖、涨度湖、汤逊湖、肖四海湖)不同水体鳜为研究材料,利用微卫星遗传标记对其种群遗传结构进行分析,结果表明:由期望杂合度(He)和多态信息含量指数(PIC)检测的遗传多样性由大到小的顺序为:长江、通江湖泊群体>无放流陆封型湖泊群体>放流的陆封型湖泊群体,并且发现一些稀有等位基因位点在陆封型湖泊鳜群体中消失;由杂合度检验可以看出,所有群体在绝大多数位点都呈现杂合过剩现象,经过哈代-温伯格平衡检验,显示均显著偏离哈代-温伯格平衡(Pst为0.2727,显示群体间已发生较大遗传分化,其变异主要体现在通江湖泊和陆封型湖泊之间,同时由于陆封型湖泊之间放流管理模式的不同,亦会产生中度分化。研究结果表明,江湖阻隔是造成定居性鱼类鳜种群间遗传分化的重要原因之一。