CRB: Inbreeding Depression and Adaptive Genetic Variation in Gila Topminnows

CRB：希拉顶米诺鱼的近交抑制和适应性遗传变异

• 批准号: 9322655
• 负责人: Philip Hedrick
• 金额: $ 22.82万
• 依托单位: Arizona State University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 1994
• 资助国家: 美国
• 起止时间: 1994-06-01 至 1997-11-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9322655&HistoricalAwards=false
• 关键词: CRB; Inbreeding; Depression; Adaptive; Genetic

9322655 Hedrick In this research, the PI's will examine inbreeding depression over two generations for several components of fitness in different populations of the endangered species, the Gila topminnow. In a series of experiments, the PI's will compare fitness values between progeny of sib matings and the progeny of random matings between individuals within the same population. Next, the PI's will measure the effect of crossing individuals from different populations on the same fitness components. Populations of topminnows were thought to undergo periodic oscillations with population bottlenecks, local extinctions, recolonizations, and even crossing between populations. As a result, it is important in determining the pattern of genetic variation over populations whether crosses between individuals from different populations are no different than within population crosses, are heterotic, or show outbreeding depression. These crosses should give information on whether the different populations are fixed for detrimental alleles that can be covered up by outcrossing or are so different that F1 and F2 progeny have reduced fitness. The major histocompatibility complex may be the most important adaptive genetic region in mammals, conferring resistance to various pathogens. Recent work in fish has demonstrated that there is extensive variation for MHC in several species and that the pattern of variation is consistent with that in mammals. The PI's will document the extent and pattern of MHC in the four metapopulations of the Gila topminnow to determine if this species, which is fixed for allozymic variation in all populations except one, has variation in this important adaptive region. %%% The primary principles of conservation genetics are related to inbreeding depression and the retention of potentially adaptive genetic variation. It is therefore of fundamental importance to characterize both the extent of inbreeding depression and adaptive genetic variation in particular endangered species. In this study, the PI's have a unique opportunity to measure these values in the endangered Gila topminnow which exists in only four natural populations in sub-basins of springs and headwater streams in Arizona. In addition, this research will add further information on variability in the major histocompatibility complex which has received only limited attention in fish. ***

9322655 Hedrick 在这项研究中，PI 将检查两代人的近交衰退，以了解濒危物种吉拉顶鲦鱼不同种群的健康状况。在一系列实验中，PI 将比较同胞交配的后代与同一群体内个体之间随机交配的后代之间的适应度值。接下来，PI 将测量来自不同群体的个体对相同适应度成分的交叉影响。人们认为，顶米鱼的种群会经历周期性波动，包括​​种群瓶颈、局部灭绝、重新殖民，甚至种群之间的杂交。因此，在确定群体遗传变异模式时，重要的是来自不同群体的个体之间的杂交是否与群体内的杂交没有什么不同、是杂种优势还是表现出近交衰退。这些杂交应该提供有关不同群体是否固定有害等位基因的信息，这些等位基因可以通过异交掩盖，或者差异如此之大以至于F1和F2后代的适应性降低。 主要组织相容性复合体可能是哺乳动物中最重要的适应性遗传区域，赋予对各种病原体的抵抗力。最近对鱼类的研究表明，几个物种的 MHC 存在广泛的变异，并且变异模式与哺乳动物中的一致。 PI 将记录毒蜥四个集合种群中 MHC 的范围和模式，以确定该物种（除一个种群外，所有种群中的异酶变异都是固定的）在这一重要的适应区域中是否存在变异。 %%% 保护遗传学的主要原理与近交抑制和潜在适应性遗传变异的保留有关。因此，表征特定濒危物种的近交衰退程度和适应性遗传变异至关重要。 在这项研究中，PI 有一个独特的机会来测量濒临灭绝的吉拉毒蜥的这些值，这种动物仅存在于亚利桑那州泉水和源头溪流子流域的四个自然种群中。此外，这项研究将增加有关主要组织相容性复合体变异性的更多信息，而这种复合体在鱼类中仅受到有限的关注。 ***