Lifetime Fitness of Hybrids in Natural Plant Populations: Testing Models for Hybrid Zones

杂交区是相关物种或其他基因不同的种群聚集在一起并产生一些可存活后代的区域。杂交在开花植物中尤其普遍，在许多动物群体中也有。进化生物学家提出了几个模型来解释杂交区遗传变异的模式。这些模型对杂交物种的自然选择做出了不同的假设，它们对长期进化有着不同的重要影响。了解维持杂交带的过程也可以应用于防止作物和相关杂草之间的杂交，以及保护发生在更常见近亲附近的稀有物种。本研究将通过比较亲本和杂交植物在田间的终生适合度来检验杂交带模型。研究人员将追踪两个亲缘关系密切的物种Ipomopsis aggregata和Ipomopsis tenuituba之间的实验杂交所产生的后代的生存和最终繁殖成功率，并将其作为种子种植在几个地方。将种植第一代和第二代杂交作物。每个模型都可以通过其独特的预测来区分杂交和亲本个体的适应度，以及这些适应度在不同环境下的变化。此外，研究人员将确定两个物种的花粉粒之间的相互作用是否会降低杂交形成的水平，并导致杂交程度的地理差异。这一目标将通过实验和计算机模拟来确定在自然种群中到达花朵的花粉混合物，并通过进行实验授粉和种子遗传分析来实现。

Campbell 9806547 Hybrid zones are areas where related species, or other genetically distinct populations, come together and produce some viable offspring. Hybridization is particularly widespread in flowering plants and also occurs in many animal groups. Evolutionary biologists propose several models to explain patterns of genetic variation across the resulting hybrid zones. These models differ in the assumptions they make about natural selection on hybrids, and they have different important consequences for long-term evolution. Understanding the processes responsible for maintaining hybrid zones can also be applied to prevention of hybridization between crops and related weeds, and to conservation of rare species that occur near more common relatives. This study will test models for hybrid zones by comparing the lifetime fitness of parent and hybrid plants in the field. The investigators will follow the survival and final reproductive success of offspring generated from experimental crosses between two closely related species, Ipomopsis aggregata and Ipomopsis tenuituba, and planted as seeds into several locations. First generation and second generation hybrids will be planted. Each model can be distinguished by its unique predictions about the fitnesses of hybrids and parental individuals and how these change across environments. In addition, the investigators will determine whether interactions between pollen grains of the two species can reduce the level of hybrid formation and contribute to geographical variation in the extent of hybridization. This goal will be met using experiments and computer simulations to determine the mixtures of pollen that reach flowers in natural populations, and by performing experimental pollinations and genetic analysis of seeds.