CRB: Inbreeding Depression and Adaptive Genetic Variation in Gila Topminnows

9322655赫德里克 在这项研究中，PI的将检查近亲繁殖抑郁症超过两代的几个组成部分的健身在不同的人口的濒危物种，吉拉topminnow。在一系列实验中，PI将比较同一种群内个体之间同胞交配的后代和随机交配的后代之间的适应度值。接下来，PI将测量来自不同种群的交叉个体对相同适应度分量的影响。人们认为，topminows的种群会经历周期性的振荡，包括种群瓶颈、局部分离、局部分化，甚至种群之间的交叉。因此，重要的是在确定的模式，遗传变异的群体之间的杂交是否从不同的群体是没有什么不同的个人之间的杂交比群体内的杂交，是杂种优势，或显示远系繁殖衰退。这些杂交应该提供不同群体是否固定有害等位基因的信息，这些有害等位基因可以被异交所掩盖，或者是如此不同，以至于F1和F2后代的适合度降低。 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抗性。最近在鱼类中的研究表明，MHC在几个物种中存在广泛的变异，并且变异模式与哺乳动物一致。PI的将记录的程度和模式的MHC在四个集合种群的Gila topminnow，以确定该物种，这是固定的等位酶变异的所有人口，除了一个，有变化，在这个重要的适应性区域。 保护遗传学的主要原则与近交衰退和保留潜在的适应性遗传变异有关。因此，它是至关重要的特点，特别是濒危物种的近亲繁殖衰退和适应性遗传变异的程度。 在这项研究中，PI的有一个独特的机会来衡量这些值在濒危的Gila topminnow存在于只有四个自然种群的子流域的泉水和源头流在亚利桑那州。此外，这项研究将增加更多的信息，在主要组织相容性复合体的变化，这只得到了有限的关注，在鱼类。 ***

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. ***