Extent and Mechanisms of Gene Flow Limitation between Divergent Populations

不同种群之间基因流动限制的程度和机制

• 批准号: 9207573
• 负责人: Sara Via
• 金额: --
• 依托单位: Cornell Univ - State: AWDS MADE PRIOR MAY 2010
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 1992
• 资助国家: 美国
• 起止时间: 1992-12-15 至 1996-11-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9207573&HistoricalAwards=false
• 关键词: Extent; Mechanisms; Gene; Flow; Limitation

Pronounced local adaptation and genetic divergence have been found between closely adjacent pea aphid populations on alfalfa and clover. However, little is known about the balance between selection and gene flow that currently maintains the observed genetic differentiation of aphids on the two hosts. On both hosts, the performance of transplanted individuals is much lower than that of residents, indicating strong disruptive selection. Pea aphids are capable of flying between fields of the different crops and specialist clones can interbreed and produce viable offspring, so migration and gene flow are physically possible. How much gene flow actually takes place? The major questions addressed in this proposal are (1) is the host-associated divergence maintained by selection in the face of free gene flow between crops? and (2) if, as we expect, gene flow is restricted, by what ecological and genetic mechanisms does this occur? First, the extent of inter- host gene flow will be determined using both direct and indirect methods, with measures of gene flow between fields of the same crop as a reference point. Preliminary results suggest that populations on the two crops are neither completely isolated nor panmictic. Various mechanisms that could act to limit gene flow between these divergent populations will be then evaluated, including habitat choice by alate (winged) forms, selection against migrants, phenological separations between mating population on the two crops, and reduced fitness of hybrids due to developmental failure and/or lack of adaptation to the parental environments. The results of these experiments will provide a detailed view of the mechanisms by which closely adjacent populations in different habitats remain genetically differentiated despite the potential to interbreed. This study represents a unique opportunity to study mechanisms of local adaptation and population divergence. These experiments will also provide a case study of gene flow restriction that has implications for the study of speciation, and the process by which insect pests adapt to specific crop plants.

在苜蓿和三叶草上的豌豆蚜种群间存在明显的局部适应和遗传分化。然而，很少有人知道选择和基因流之间的平衡，目前保持观察到的遗传分化的蚜虫在两个主机。在这两个主机上，移植的个人的表现是远远低于居民，表明强烈的破坏性选择。豌豆蚜虫能够在不同作物的田地之间飞行，专业克隆可以杂交并产生可存活的后代，因此迁移和基因流动在物理上是可能的。到底有多少基因流在发生？在这个建议中解决的主要问题是（1）是主机相关的分歧保持选择在面对作物之间的自由基因流？（2）如果如我们所料，基因流动受到限制，这是通过什么生态和遗传机制发生的？首先，将使用直接和间接方法来确定宿主间基因流动的程度，以同一作物田间之间的基因流动作为参考点。初步结果表明，两种作物上的种群既不是完全隔离的，也不是全混的。各种机制，可以采取行动，以限制这些不同的人群之间的基因流，然后将进行评估，包括栖息地的选择有翅（翅）的形式，选择对移民，两种作物的交配人口之间的物候分离，并减少健身的杂交由于发育失败和/或缺乏适应父母的环境。这些实验的结果将提供一个详细的机制，在不同的栖息地密切相邻的人口保持遗传差异，尽管杂交的潜力。这项研究是一个独特的机会，研究当地的适应机制和人口的分歧。这些实验还将提供一个基因流限制的案例研究，这对物种形成的研究以及害虫适应特定作物的过程有影响。