A Genome-Wide Investigation of Factors Causing Postzygotic Isolation Between Two Mimulus Species.

[00:75704]达尔文不明白新物种之间的繁殖障碍是如何进化的。毕竟，很难想象自然选择如何能定期导致进化出不适应的特征，比如杂交后代的过早死亡或不育。今天，人们了解染色体重排（或下显性位点）和位点之间的上位性相互作用可导致杂交不育。这些选择引发了截然不同的进化过程，因此区分它们是理解物种起源的基本步骤。本研究将测试染色体重排和遗传相互作用在引起野花种Mimulus guttatus和M. nasutus杂交中所观察到的部分杂交不育中的作用。该项目利用遗传标记从异种基因组背景下的每个物种中分离出染色体片段，并在普通花园实验中测试它们的适合度。个体不相容性因子的数量、影响、表达模式和遗传基础将被确定。这些实验解决了杂交不育进化的基本问题，因此将有助于我们了解新物种是如何起源的。

0075704WillisDarwin did not understand how reproductive barriers between new species could evolve. After all, it is hard to imagine how natural selection alone could regularly result in the evolution of maladaptive traits like the premature death or sterility of hybrid offspring. Today it is understood that chromosomal rearrangements (or underdominant loci) and epistatic interactions between loci can cause hybrid sterility. These alternatives invoke vastly different evolutionary processes, so differentiating between them is a fundamental step in understanding the origin of species. The proposed research will test for the action of chromosomal rearrangements and genetic interactions in causing the partial hybrid sterility observed in crosses between the wildflower species Mimulus guttatus and M. nasutus. The projects use mapped genetic markers to isolate chromosomal segments from each species in the heterospecific genomic background, and test their fitness in common garden experiments. The number, effects, patterns of expression, and genetic basis of individual incompatibility factors will be determined. These experiments address fundamental issues underlying the evolution of hybrid sterility, and so will contribute to our understanding of how new species originate.