The Genetic Basis of Reproductive Isolation: QTL Mapping and Hybrid Zone Analysis Between Aquilegia Formosa and A. pubescens

9726272 Hodges耧斗菜属的两种，A. formosa和A. pubescens，具有非常不同的花形态，主要由不同的动物授粉。福尔摩沙的花朵呈红色，下垂，短刺，由蜂鸟传粉；短毛草的花朵呈白色，直立，长刺，由飞蛾传粉。虽然这两个物种在控制杂交中完全相容，但由于它们的花朵不同，它们在自然界中很少杂交。这两个物种的分布在加州内华达山脉南部重叠，在那里形成了狭窄的杂交带。我们将利用动物和植物育种技术确定导致花形态差异的基因数量。因为杂交区确实发生在这些物种重叠的地方，一个物种的基因不受自然选择的影响，可以穿透杂交区进入其他物种。然而，受自然选择影响的基因被阻止进入替代物种。我们将通过测量每个基因组片段能够穿透杂交区外的程度来确定自然选择是如何作用于每个基因组片段的。进化生物学的一个主要目标是了解导致生殖隔离的性状的遗传基础。这些性状对生物多样性的产生和维持负有责任。许多科学家认为，物种之间的大多数适应性差异源于许多小的遗传变化的积累，而另一些科学家则认为它们源于具有大影响的少数变化。这个问题一直没有解决，因为详细的遗传研究仅限于少数模式生物。此外，对物种分离重要的性状数量和基因组比例尚不清楚。综合基因组作图技术和杂交区分析技术，将有可能对物种分离的遗传学进行详细的检查。

9726272 Hodges Two species of the columbine genus Aquilegia, A. formosa and A. pubescens, have very different floral morphologies and are predominantly pollinated by different animals. A. formosa has red, pendent, short-spurred flowers pollinated by hummingbirds and A. pubescens has white, upright, long-spurred flowers pollinated by hawkmoths. While these two species are fully compatible in controlled crosses, they rarely crossbreed in nature due to the differences in their flowers. The two species' distributions overlap in the southern Sierra Nevada mountains of California where narrow hybrid zones form. We will determine the number of genes responsible for the differences in floral morphology by utilizing techniques developed for animal and plant breeding. Because hybrid zones do occur where these species overlap, genes from one species that are not affected by natural selection can penetrate beyond the hybrid zone into the other species. However, genes that are affected by natural selection are prevented from penetrating the alternate species. We will determine how natural selection acts on each segment of the genome by measuring the degree it is able to penetrate beyond the hybrid zone. A major goal of evolutionary biology is to understand the genetic basis of traits conferring reproductive isolation. These traits are responsible for the generation and maintenance of biological diversity. Many scientists believe that most adaptive differences between species arise from the accumulation of many small genetic changes while others believe that they arise from a few changes with large effects. This issue has remained unresolved because detailed genetic studies have been limited to only a few model organisms. In addition, the number of traits and the proportion of the genome important for species isolation is unknown. By synthesizing genome mapping techniques with hybrid zone analyses a detailed examination of the genetics of specie s isolation will be possible.