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

9707331罗斯最近将相当多的注意力集中在创始人事件和其他类型的种群规模(瓶颈)严重减少后遗传多样性的减少上。引起这种兴趣的一个原因是，遗传变异的减少可能会影响种群随后对自然选择做出反应的能力。此外，瓶颈之后遗传变异的性质和程度的变化可能会导致父母和创始人群体之间的遗传不相容，其中一个结果可能是物种形成。因此，伴随瓶颈而来的基因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，并且具有应用意义，因为受瓶颈影响的濒危物种可能缺乏应对随后环境变化的能力。这个项目的目的是描述一个有充分记录的创始人事件对火蚁Solenopsis invicta野生种群中五种不同类别遗传标记变异的影响。使用的标记包括78个来自蛋白质电泳的核标记，7个微卫星DNA基因座，RAPDDNA标记，负责性别决定的一个或多个基因座，以及线粒体DNA标记。这五组标记的结果对于研究瓶颈的影响是互补的，因为它们具有不同的遗传结构，处于不同的选择制度下，并且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，通常不处于强选择之下。微卫星是位于非编码区的重复核序列，具有广泛的多态性。RAPD是随机扩增的核序列，也假设在非编码区，显示出简单的存在/不存在多态。性别决定基因是在强选择下的一个调节元件，它保持着与微卫星相当甚至超过的广泛的多态。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形成对比。综合结果将被用来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。这一结果还可以估计组成美国原始创始人群体的火蚁后的数量。

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.