Effects of a Founder Event on Genetic Diversity in the Fire Ant Solenopsis invicta

9707331罗斯相当多的注意力最近集中在遗传多样性的减少，以下创始人事件和其他类型的严重减少人口规模（瓶颈）。 这种兴趣的一个原因是，减少遗传变异可能会影响种群随后对自然选择作出反应的能力。 此外，瓶颈之后遗传变异的性质和程度的变化可能导致亲本和创始人群体之间的遗传不相容性，其结果之一可能是物种形成。 因此，伴随瓶颈的遗传变化具有基本的科学意义，因为它们可能在适应和物种多样化的自然过程中发挥作用，也具有应用意义，因为受到瓶颈影响的濒危物种可能缺乏对随后的环境变化作出反应的能力。 该项目的目的是描述一个有据可查的创始人事件对火蚁红火蚁野生种群中五个不同类别的遗传标记变异的影响。 所用的标记有78个来自蛋白质电泳的核标记、7个微卫星DNA位点、64个RAPD DNA标记、负责性别决定的位点和线粒体DNA标记。 这五组标记的结果是互补的研究瓶颈的影响，因为他们有不同的遗传结构，是在不同的选择制度，并具有不同的遗传模式。电泳标记代表蛋白质编码的核基因座，具有适度的变异，通常不在强选择下。 微卫星是一种在非编码区的重复序列，具有广泛的多态性。 RAPD是随机扩增的核序列，也被认为是在非编码区，显示简单的存在/不存在多态性。 性别决定基因座是强选择条件下的一个调控元件，它保持着与微卫星相当甚至超过微卫星的广泛多态性。 最后，线粒体DNA提供了一组母系遗传的标记，与四类核基因的双亲遗传相反。 复合结果将用于测试预测瓶颈如何影响各类基因以及瓶颈种群的进化潜力如何改变的理论。 这些结果也可以用来估计在美国构成原始建立者种群的火蚁后的数量。

9707331 Ross Considerable attention has focused recently on the reduction in genetic diversity that follows founder events and other types of severe reductions in population size (bottlenecks). One reason for this interest is that reduced genetic variation may affect the subsequent ability of populations to respond to natural selection. Moreover, changes in the nature and extent of genetic variation following a bottleneck may lead to genetic incompatibilities between parental and founder populations, one outcome of which may be speciation. Thus, the genetic changes accompanying bottlenecks are of basic scientific interest because of their possible role in the natural processes of adaptation and species diversification, and of applied interest because endangered species subjected to bottlenecks may lack the ability to respond to subsequent environmental change. The aim of this project is to describe the effects of a well-documented founder event on variation in five different classes of genetic markers in wild populations of the fire ant Solenopsis invicta. The markers to be used are 78 nuclear markers derived from protein electrophoresis, seven microsatellite DNA loci, 64 RAPD DNA markers, the locus or loci responsible for sex determination, and markers of the mitochondrial DNA. Results from these five sets of markers are complementary for studying the effects of a bottleneck because they have different genetic architectures, are under different selective regimes, and have different modes of inheritance. Electrophoretic markers represent protein-encoding nuclear loci with modest variation that generally are not under strong selection. Microsatellites are repetitive nuclear sequences in non-coding regions that harbor extensive polymorphism. RAPDs are randomly amplified nuclear sequences also assumed to be in non-coding regions that display simple presence/absence polymorphisms. The sex-determining locus is a regulatory element under strong selection that maintains extensive polym orphism comparable to or even surpassing that of microsatellites. Finally, mitochondrial DNA provides a set of markers that are maternally inherited, in contrast to the biparental inheritance of the four classes of nuclear genes. The composite results will be used to test theories that predict how bottlenecks affect various classes of genes and how the evolutionary potential of bottlenecked populations is altered. The results also may allow estimation of the number of fire ant queens constituting the original founder population in the U.S.