Theoretical Studies in Ecological and Population Genetics

亚斯穆森980462高度的遗传变异是自然种群的一个显著和普遍的特征。这种变化的迹象在我们周围的世界中很容易看到。例如，植物的花色、蝴蝶的翅膀图案、人类和其他生物的疾病易感性等特征存在着广泛的多样性，所有这些都有遗传基础。遗传变异的全部范围是在分子水平上发现的，实验室对基因产物和DNA序列的分析表明，单个基因在一个群体中可能有数十种、甚至100种或更多不同的形式。这种巨大的遗传多样性具有至关重要的进化重要性，因为它决定了适应不断变化的环境条件的能力，这对物种的长期生存至关重要。例如，花色的变化可以让植物吸引新的昆虫传粉者，从而确保成功繁殖，而蝴蝶翅膀图案的变化可以减少鸟类等视觉捕食者的发现和捕食，后者往往专注于有限的一组搜索图像。同样，免疫相关基因的变异可以使一个种群在新病原体引发的流行病中幸存下来。由于遗传多样性扮演着如此重要的角色，进化遗传学的一个主要目标是识别和理解自然种群中巨大的遗传多样性的原因。拟议的研究将为这一基本问题提供一种新的方法，全面评估当个体的存活率和繁殖率随时间变化时，随着种群遗传组成的变化而发生永久遗传变异的可能性。这种依赖于频率的选择在生态学上很重要，被认为有助于在广泛的生物体中保持遗传多样性。然而，到目前为止，人们对这种广泛存在的选择形式保持自然种群中发现的高遗传变异的真正潜力知之甚少。本提案将在一系列新的数学模型和计算机模拟的发展和广泛分析的基础上，启动对这一关键问题的长期理论研究。将对遗传多样性的模式和水平进行详细的描述，无论是在单独的频率依赖选择下，还是在新形式的基因在种群中不断出现的生物现实情景下。最后一个关键步骤是将结果行为与观察到的数据进行比较。总而言之，这些结果将为频率依赖选择在多大程度上解释自然界中发现的高水平遗传变异提供亟需的评估。

Asmussen 980462 A high degree of genetic variation is a striking and universal feature of natural populations. A hint of this variability is easily seen in the world around us. For instance, there is a wide diversity in such characters as flower color in plants, wing patterns in butterflies, and disease susceptibility in humans and other organisms, all of which have a genetic basis. The full extent of genetic variation is found at the molecular level, where laboratory analyses of gene products and DNA sequences reveal that a single gene may have dozens or even a hundred or more different forms in a population. This great genetic diversity is of vital evolutionary importance because it determines the ability to adapt to changing environmental conditions, which is critical to the long-term survival of species. Variation in flower color, for example, can allow plants to attract new insect pollinators, thereby ensuring successful reproduction, while variation in butterfly wing patterns can reduce detection and predation by visual predators such as birds, which tend to focus on a limited set of search images. In the same way, variation in immune-related genes can allow a population to survive an epidemic induced by a new pathogen. Because genetic diversity plays such a critical role, a major goal of evolutionary genetics is to identify and understand the forces that account for the vast genetic variability in natural populations. The proposed research will provide a new approach to this fundamental question by comprehensively evaluating the potential for permanent genetic variation when the rate of survival and reproduction of individuals changes through time as a function of the changing genetic composition of the population. Such frequency-dependent selection is ecologically important and thought to facilitate the maintenance of genetic diversity in a wide range of organisms. To date, however, little is known about the true potential of this widespread form of selection to maintain th e high genetic variation found in natural populations. The present proposal will initiate a long-term, theoretical investigation of this key issue, based on the development and extensive analysis of a series of novel mathematical models and computer simulations. A detailed characterization will be made of the patterns and levels of genetic diversity, both under frequency-dependent selection alone and in the biologically realistic scenario in which new forms of genes constantly arise in the population. The final, critical step will be to compare the resulting behavior to observed data. Together, the results will provide a much-needed evaluation of the extent to which frequency-dependent selection can explain the high levels of genetic variation found in nature.