Evolutionary genomics of plant adaptation and speciation

跨物种交配或杂交的频率有多高？在杂交之后，物种之间的界限会发生什么？杂交有时是否有助于形成新的性状或新的物种？此外，当基因不同的植物或动物杂交时，经常看到的杂交活力的遗传基础是什么？这些是我们要解决的基本生物学问题。 我们将分析杂交在阻止基因在野生向日葵物种之间移动的屏障上的效果。进化生物学家曾认为，对于物种的形成，基因流动的障碍必须是绝对的。然而，现在看来，基因组的某些部分可能受到保护，不受物种间基因流动的影响，而其他部分则没有。这项提案要解决的一个基本问题涉及个体“物种形成”基因提供的保护程度。 物种间的杂交有时也被视为一种适应的刺激。我们将测试基因的杂交组合是否促进了谜题向日葵对盐碱地的适应。我们还将查明导致野生和栽培向日葵杂交活力的基因变化。这些遗传信息将有助于培育耐盐性向日葵，并从向日葵和其他作物的杂交育种计划中提高产量。 最后，在植物和动物物种基因数据库的基础上，我们将搜索现代和古代杂交的遗传特征。这些分析有望产生关于杂交在进化中无处不在的范式转换结果。

How frequent is cross-species mating or hybridization? What happens to the boundaries between species following hybridization? Can hybridization sometimes contribute to the formation of new traits or new species? Also, what is the genetic basis of the hybrid vigour often seen when genetically different plants or animals are crossed? These are the basic biological questions we will tackle. We will analyze the effects of hybridization on barriers that prevent the movement of genes between wild sunflower species. Evolutionary biologists once believed that for species to form, barriers to gene flow must be absolute. However, it now appears that some parts of the genome may be protected from interspecific gene flow, while others are not. A fundamental question to be addressed by this proposal concerns the degree of protection provided by individual "speciation" genes. Hybridization between species is also sometimes viewed as a stimulus for adaptation. We will test whether hybrid combinations of genes have facilitated the adaptation of the puzzle sunflower to salty habitats. We also will pinpoint the genetic changes responsible for hybrid vigour in wild and cultivated sunflowers. This genetic information will facilitate efforts to breed salt tolerant sunflowers and to increase yields from hybrid breeding programs in sunflowers and other crops. Finally, building on databases of genes for plant and animal species, we will search for the genetic signature of both recent and ancient hybridization. These analyses promise to yield paradigm-shifting results about the ubiquity of hybridization in evolution.