Estimating Gene Flow into Tropical Forest Fragments

虽然对热带树种遗传多样性的调查数量众多，足以做出一些概括（种群内多样性高，种群间多样性相对较低，物种间遗传多样性差异很大），但我们对影响热带树种遗传多样性水平和分布的潜在机制知之甚少。热带树木种群之间相对较低的分化水平间接表明，基因在相当大的地理距离（5-10公里）上的移动是很高的，但目前很少有研究对基因移动进行定量估计。这些现有的估计与在人群中看到的分化程度是一致的。不幸的是，热带森林的物种丰富度和热带树木可获得的花粉和种子传播剂的广泛范围使基于少数研究的概括充其量是有问题的。拟议的研究将增加在自然条件下可以估计基因流动的物种的数量。这项研究的比较性质，虽然基于相对较少的物种，将扩展我们对热带树种基因运动的认识，到目前为止还没有研究过的几种授粉综合征。这项研究的完成将极大地扩展我们对热带森林基因运动的认识。通过研究花粉在孤立森林碎片中的有效迁移，我们将把我们的进化研究扩展到应用保护生物学的领域。任何以保护森林树种及其遗传资源为目标的管理计划都需要知道森林片段之间基因移动的程度以及它们经历的近亲繁殖的程度。此外，我们的工作将开始确定隔离距离对基因流水平的影响，以及这些关系如何在具有不同传粉综合征的物种中变化。了解基因运动的水平及其发生的空间尺度，可能最终允许开发适应农业发展的景观水平设计，同时保护热带树种的生物和遗传多样性。***

9307878 Hamrick While surveys of genetic diversity in tropical tree species are numerous enough to make some generalizations (high within population diversity, relatively low diversity among populations, much species-to-species variation in genetic diversity) We know very little about the underlying mechanisms that influence the levels and distribution of genetic diversity in tropical trees. The relatively low levels of differentiation seen among tropical tree populations indirectly indicates that gene movement over rather large geographic distances (5-10km) is high, but here are very few studies available that have made quantitative estimates of gene movement. Those estimates that are available are consistent with the levels of differentiation seen among populations. Unfortunately, the species richness of tropical forest and the wide array of pollen and seed dispersal agents available to tropical trees makes generalizations based on a few studies questionable at best. The proposed research will increase the number of species for which estimates of gene flow are available under natural conditions. The comparative nature of this research, while based on a relatively few species will extend our knowledge of gene movement in tropical tree species to several pollination syndromes that have not been studied to date. Upon its completion this research will greatly extend our understanding of gene movement in tropical forest.%%% By studying effective pollen immigration into isolated forest fragments we will extend our evolutionary studies into the realm of applied conservation biology. Any management plan with the goal to preserve forest tree species and their genetic resources will need to know the degree of gene movement among forest fragments and the levels of inbreeding they experience. Also our work will begin to determine the effects of isolation distance on levels of gene flow and how these relationships vary for species with different pollinati on syndromes. Knowledge of the levels of gene movement and the spatial scales at which it occurs may ultimately allow the development of landscape level designs that accommodate agricultural development but at the same time preserve the biological and genetic diversity of tropical tree species.***