中国板栗居群间等位酶基因频率的空间分布

中国板栗21个自然群间等位酶遗传变异的空间自相关分析及F－统计分析结果表明：其多数等位基因频率在居群间呈随机分布模式,缺乏一定的空间结构;而部分等位基因表现为渐变或双向渐变的非随机分布模式,又具有特定空间结构。中国板栗遗传变异空间结构模式的形成可能是长距离基因流、自然气候、人类活动、地理距离隔离等诸因素综合作用的结果。文中还就居群等位基因分布格局的成因进行了讨论：在第四纪冰川后,中国板栗以长江流域中下游的孑遗中心为起点,等位基因分别沿着向北和向南的不同方向迁移形成现在的居群结构;季风气候和人类活动干扰是削弱居群分化的主要因素,而基于环境梯度的选择,是形成由北向南渐变分布的原因。     

荷叶铁线蕨等位酶分析初步研究

荷叶铁线蕨 ( Adiantum reniforme var.sinense)是铁线蕨科铁线蕨属肾叶铁线蕨的一个变种〔1〕,分布于重庆市万县、石柱等县的沿江近 1 0 0 km长的狭长地段 ,分布高度局限于海拔 80～ 430 m之间 〔2〕。受其自身生物学、生态学习性的局限和人为的破坏 ,该物种正濒于灭绝的边缘。三峡工程修建后 ,库区内1 75m线以下的地区将被淹没 ,将更加剧该物种的濒危程度。为了挽救这一物种已经采取了许多措施 ,迁地保护是其中的重要措施之一 ,中国科学院武汉植物研究所在这一方面已经做了一些工作 〔3～ 5〕。为了有效地实施迁地保护 ,保存该物种的大部…     

栗属中国特有种居群的遗传多样性及地域差异

采用超薄平板聚丙烯酰胺等电聚焦技术对栗属（Ｃａｓｔａｎｅａ（Ｔｏｕｒｎ．）Ｌ．）３个中国特有种即中国板栗（Ｃ．ｍｏｌｉｓｉｍａＢＬ．）、茅栗（Ｃ．ｓｅｇｕｉｎｉＤｏｄｅ．）和锥栗（Ｃ．ｈｅｎｒｙｉ（Ｓｋａｎ）Ｒｅｈｄ．ｅｔＷｉｌｓ．）的３０个居群,１２个酶系统的２０个位点进行了遗传多样性与遗传结构分析。结果表明：中国板栗在种和居群水平都具有较茅栗、锥栗高的遗传多样性（Ｐ分别为９０．０％和８４．７％,Ｈｅ分别为０．３１１和０．２９５）,尤以长江流域居群表现显著,揭示了长江流域的神农架及周边地区为中国板栗的遗传多样性中心。Ｎｅｉ的遗传一致度测量结果显示中国板栗和茅栗的亲缘关系最近,并且地理距离和遗传距离有一定的相关性。中国板栗、茅栗和锥栗的遗传分化程度逐渐增大,Ｇｓｔ分别为７．５％、１０．９％和２２．１％;基因流（Ｎｍ）分别为３．２０、２．０５和０．８８。研究结果为探明栗属起源、系统进化及制定保育策略提供了科学依据。     

栗属中国特有种居群的遗传多样性及地域差异

Genetic variability in 30 populations of three endemic Castanea (Tourn.) L. species (C. moUissima BI., C. seguinii Dode. and C. henryi (Skan) Rehd. et Wils. ) in China was investigated using isoelectric focusing in thin-layer polyacrylamide slab gels at 20 loci coding for 12 enzyme systems. C. mollissima was found to possess a significant higher value of genetic variability than that of the other two species. The percentage of polymorphic loci (P) and the expected heterozygosity (He) were 90.0% and 0. 311 at the species level, respectively; while P = 84.7 %, He = 0.295 at the population level. Comparison of the population genetic variability of C. mollissima in three regions of China, the populations from the Yangtze River valley showed a markedly higher mean expected gene heterozygosity. The results provided additional evidence that the Yangtze River valley, particularly in Shennongjia area, was the center of the genetic diversity of C. moUissima. Genetic relationships among populations and species were assessed by Nei genetic identity (I) and standard genetic distance (D), suggesting that C. mollissima and C. seguinii have a closer relationship, and genetic distances were correlated with geographical distances among populations. Genetic differentiation between populations in C. mollissima, C. seguinii and C. henryi was 7.5%, 10.9% and 22.1%, respectively, and the gene flow rate (Nm) was 3.20, 2.05 and 0.88 respectively. The study provides useful imfonnation for understanding of the origin and evolutionary events in genus Castanea and planning an effective conservation strategy.