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

坎贝尔9806547杂交区是相关物种或其他遗传上截然不同的种群聚集在一起并产生一些可存活后代的区域。杂交在开花植物中特别普遍，也在许多动物群体中发生。进化生物学家提出了几个模型来解释由此产生的杂交区的遗传变异模式。这些模型对杂交种的自然选择的假设不同，对长期进化也有不同的重要后果。了解负责维持杂交区的过程也可以用于防止作物与相关杂草之间的杂交，以及保护出现在较常见近亲附近的稀有物种。这项研究将通过比较亲本和杂交植株在田间的寿命适合度来测试杂交区的模型。研究人员将跟踪两个亲缘关系密切的物种Ipomopsis ggregata和Ipomopsis tenuituba之间的试验性杂交产生的后代的存活和最终繁殖成功，并将其作为种子种植到几个地点。将种植第一代和第二代杂交种。每一种模型都可以通过其对杂交后代和亲本个体适合性的独特预测以及这些预测如何在不同环境中发生变化来区分。此外，研究人员将确定这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自然种群中到达花朵的花粉混合物，并通过对种子进行实验性授粉和遗传分析来实现。

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.