伞裙追寄蝇不同地理种群遗传多样性的ISSＲ分析

为从分子水平探索不同地区伞裙追寄蝇种群间的内在联系,本文利用ISSR分子标记技术对8个不同地区伞裙追寄蝇自然种群进行遗传多样性、种群间分化程度以及聚类分析等研究。结果表明:筛选出11对多态性稳定的ISSR引物,对8个地区伞裙追寄蝇群体的80个个体进行PCR扩增,共获得166个重复性好且清晰可辨的ISSR条带,平均每条引物扩增出15.0909个片段,且均为多态性条带,多态信息含量(PIC)为0.8441-0.8653;香农信息指数(I)为0.1240-0.3455;Nei's遗传多样性指数(H)为0.0841-0.2285;基因分化率(Gst)为28.78%,基因流(Nm)的均值为1.5702,即遗传变异主要存在于个体之间,不同种群间基因交流处于中等水平;8个地区伞裙追寄蝇种群被划分为4个类群,种群间的遗传分化与地理距离呈正相关关系。     

Life‐history traits and geographical divergence in wild rice (Oryza rufipogon) gene pool in Indochina Peninsula region

Indochina Peninsula is the primary centre of diversity of rice and lies partly in the centre of origin of cultivated rice (Oryza sativa) where the wild ancestor (Oryza rufipogon) is still abundant. The wild gene pool is potentially endangered by urbanisation and the expansion of agriculture, and by introgression hybridisation with locally cultivated rice varieties. To determine genetic diversity and structure of the wild rice of the region we genotyped nearly 1000 individuals using 20 microsatellite loci. We found ecological differentiation in 48 populations, distinguishable by their life‐history traits and the country of origin. Geographical divergence was suggested by isolation of the perennial Myanmar populations from those of Cambodia, Laos and Thailand. The annual types would be most likely to have lost genetic variation because of genetic drift and inbreeding. The growing of cultivated and wild rice together, however, gives ample opportunities for hybridisation, which already shows signs of genetic mixing, and will ultimately lead to replacement of the original wild rice gene pool. For conservation we suggest that wild rice should be conserved ex situ in order to prevent introgression from cultivated rice, along with in situ conservation in individual countries for the recurrent evolutionary process through local adaptation, but with sufficient isolation from cultivated rice fields to preserve genetic integrity of the wild populations.     

福建省主要入侵植物空间分异及其影响因素

在实地调查数据的基础上,本研究结合GIS空间分析技术和地理探测器模型,分析福建省入侵植物空间分布情况,以及地理与社会环境因子及其交互作用对入侵植物分布的影响.结果表明:福建省共记录入侵植物82种,其中,优势科为菊科,小蓬草、藿香蓟和空心莲子草出现频次最高.沿海区域的入侵植物物种数量多于内陆区域,福州和厦门为福建省外来入侵植物的两大热点地区.入侵植物在不同海拔均有分布,但入侵植物的种类随着海拔的升高总体呈下降趋势.地理探测器分析显示,自然环境因子中降水和社会经济因子中路网密度、人口密度是入侵植物空间分布的主要影响因子.各因子的空间交互作用会正向影响入侵植物的空间分布,这反映出入侵植物空间分布影响要素的复杂性.综上,将地理探测器应用到入侵植物研究领域是可行的,筛选出的环境指示因子可用于监测福建省入侵植物的适生区,从而为采取有效的防控措施提供科学依据.     

福建梅花山自然保护区蕨类植物区系研究

通过野外调查和资料整理,统计分析梅花山自然保护区蕨类植物区系组成和分布区类型,比较其与周边相邻4个自然保护区的蕨类植物区系的相似性。结果表明:(1)梅花山自然保护区共有蕨类植物42科83属189种,科、属组成优势现象明显,区系起源古老。(2)分布区类型在科、属级水平上以泛热带分布和世界分布为主,种级水平以热带亚洲分布、东亚分布和中国特有分布为主,热带亲缘明显,具有由热带向温带过渡的性质。(3)在地理亲缘关系上,梅花山与梁野山的蕨类植物区系联系最为紧密,与圭龙山的关系次之,与热带区系性质较强的南靖南亚热带雨林自然保护区和典型的中亚热带性质的武夷山自然保护区的种子植物区系联系较为疏远,具有从南亚热带向中亚热带过渡的明显特点。     

Evolutionary constraint on low elevation range expansion: Defense‐abiotic stress‐tolerance trade‐off in crosses of the ecological model Boechera stricta

Most transplant experiments across species geographic range boundaries indicate that adaptation to stressful environments outside the range is often constrained. However, the mechanisms of these constraints remain poorly understood. We used extended generation crosses from diverged high and low elevation populations. In experiments across low elevation range boundaries, there was selection on the parental lines for abiotic stress‐tolerance and resistance to herbivores. However, in support of a defense‐tolerance trade‐off, extended generation crosses showed nonindependent segregation of these traits in the laboratory across a drought‐stress gradient and in the field across the low elevation range boundary. Genotypic variation in a marker from a region of the genome containing a candidate gene (MYC2) was associated with change in the genetic trade‐off. Thus, using crosses and forward genetics, we found experimental genetic and molecular evidence for a pleiotropic trade‐off that could constrain the evolution of range expansion.