野古草种群克隆的遗传变异和遗传结构

用酶电泳法和同工酶分析对东北松嫩草原西北部野古草种群克隆遗传变异性和种群遗传结构做了探讨。讨论了遗传多样性、地理距离和遗传距离之间的关系、大种群和小种群的遗传变异性和种群间的基因流 ;种群间 ,包括大种群和小种群间基因流、遗传和地理距离对遗传多样性的影响、昆虫和风传粉、种群籽苗的补充、遗传多样性的发生和保持 ,自交不亲和性和无性繁殖及体细胞突变

Genetic variability and genetic structure in clonal population of Arundinella hirta

Authors made approach to genetic variability and genetic structure of 30 clonal populations of Arundinella hirta in northeastern Song Nen steppe in China using enzyme electrophoresis and isozome analysis. Our study obtained the following results: means of P, A, AP, Ho and He in 30 populations were 17.00%, 1.17, 2.03, 0.103 and 0.063, respectively at the population level. The population with highest allelic diversity possessed 38.71% of the total allelic diversity in our sample. All of the alleles encountered in this study can be found in eight populations, including six with unique alleles and two others (RY3 and AS1). These populations appeared in all geographic areas. At the population level, average expected heterozygosity was 0.063. Observed heterozygosity 0.103 and ranging from 0.030 to 0.184. When genetic distances among all population pairs inhabiting the same large population and all pairs inhabiting the small population in the same region were compared, we found no significant relationship between genetic and geographic distances (P>0.56), and no significant difference between the two categories (P>0.89). Genetic diversity, including allelic richness, % polymorphic loci, obeserved heterozygosity, differed signifcantly between large population and small population (P>0.21). In 15 small populations, 57 of the 63 recorded alleles were found, in 15 large populations, 57 of the 63 alleles also were found. Levels of genetic variation did differ, however, among geographic areas within the study area (P>0.04). More than 40% genetic variation (G_(ST)=0.410) may be attributed to the variation among populations. Clonal reproduction and obligate outcrossing of Arundinella hirta complicated identification of other sources of variation. Observed levels of heterozygosity within populations were greater than have been expected if ramets were the products of random sexual reproduction. Values of total inbreedings, which compare observed heterozygosity within population with expected heterozygosity based on random mating within the entire study region. Higher Fst vallues for all loci indicated significant genetic differentiation at the population level, and the values ranged from 0.0890 to 0.8849. Populations were differentiated from one another within areas roughly to the same extent as they were differentiated within the entire study region. Calculations of gene flow indicated low levels of migration among populations of Arundinella hirta. Estimates of Nm<1 showed that gene flow between populations was inadequate to counter the effects of genetic drift in local populations. Measured values of genetic variation of Arundinella hirta population in this paper were more or less approximate to values estimated by Hamrick and Godi, Wolf et al. However, changes in genetic diversity of Arundinella hirta populations differed from other reports in genetic variations among populations, within populations in more or less extent. This variations occurred not only among populations, but occurred also within ones. Gene flow between populations was low, not only between small populations but also between large populations. Population in small area dod not appear to be impoverished compared with populations in large area although small populations were separated into innumerable small populations, often disturbed by grazing and human activities. This fact illustrated that losses of genetic diversity through the combined effects of genetic drift, inbreeding, and local selection was no more severe in small populations than in large populations. We must point out that the importance of clonal reproduction and somatic mutation for plant population genetics deserves considerable future study, and this study may provide important insights into the longer term evolutionary diversification of Arundinella hirta and other long-lived clonal plant species.