Effects of Inbreeding on the Male and Female Functions of Plants

近交抑制是指近交后代（自交或近亲授粉的后代）相对于异交后代的适合度降低。一项令人印象深刻的理论预测，近亲繁殖抑制是植物花的性状（大小、形状、颜色、气味等）和交配模式进化的主要力量。在过去的一个世纪里，许多研究表明，近亲繁殖降低了植物的相对存活率和产生的种子的相对数量和质量。然而，大多数研究忽略了近亲繁殖对植物雄性（花粉）功能的影响，尽管大多数植物是雌雄同体（既产生花粉又产生种子）。此外，我们对近交衰退的程度如何随着生长（环境）条件的变化而变化知之甚少。最后，关于近亲繁殖抑制的遗传基础仍有很多争论。因此，我们将进行一系列的项目设计：1)通过雄性和雌性功能量化和比较近交抑制对生存和繁殖的影响程度；2)检查近交抑制与环境压力之间的关系；3)确定近交与适应性之间的关系。4)确定近交对男性功能抑制的近交原因。从本提案的项目中获得的数据将导致对近亲繁殖对植物雄性功能影响的第一次全面研究；他们将产生可测试的预测（以及测试这些预测所需的种子），涉及近亲繁殖抑郁症的遗传基础；它们将使我们能够更好地预测在不同环境条件下花性状的进化方向；它们将使我们能够批判性地评估围绕植物交配模式进化的理论。从实际的角度来看，我们的研究结果将对农业（例如，杂交种业将植物的自交系作为其育种计划的主要组成部分）、保护生物学（例如，保护现在只存在于小型、高度自交系种群中的濒危植物）和林业（花粉选择至关重要，因为传统的植物育种技术由于树木的长世代而失败）产生重要影响。

Stephenson 9806691 Inbreeding depression is the reduction in fitness of inbred progeny (progeny resulting from self-pollinations or pollinations by close relatives) relative to outcrossed progeny. An impressive body of theory predicts that inbreeding depression is a major force in the evolution of floral traits (size, shape, color, odor, etc. of flowers) and mating patterns in plants. Over the past century many studies have shown that inbreeding reduces relative survivorship and the relative number and quality of the seeds produced by plants. However, most studies have ignored the effects of inbreeding on the male (pollen) function of plants despite the fact that most plants are hermaphrodites (produce both pollen and seeds). Moreover, we know little about how the magnitude of inbreeding depression changes with growing (environmental) conditions. Finally, there remains much debate concerning the genetic basis of inbreeding depression. Consequently, we will perform a series of projects designed 1) to quantify and compare the magnitude of inbreeding depression on survivorship and reproduction through both the male and female functions, 2) to examine the relationship between inbreeding depression and environmental stress, 3) to determine the relationship between inbreeding and fitness across four levels of inbreeding, and 4) to determine the proximate cause of inbreeding depression on the male function. The data obtained from the projects in this proposal will result in the first comprehensive study of the effects of inbreeding on the male function of plants; they will generate testable predictions (and the seeds necessary to test these predictions) concerning the genetic basis of inbreeding depression; they will allow us to better predict the direction in which floral traits will evolve under different environmental conditions; and they will allow us to critically evaluate the theory surrounding the evolution of plant mating patterns. From a practical perspective, our findings will have important ramifications for agriculture (e.g., the hybrid seed industry uses inbred lines of plants as the major component in their breeding programs), conservation biology (e.g., the preservation of endangered plants that now exist only in small, highly inbred populations), and forestry (where pollen selection is of utmost importance because traditional plant breeding techniques fail due to the long generation time of trees).