Collaborative Research: Evolutionary tradeoffs between outcross siring success and selfing: the role of ecological context in the stability of mixed mating systems

生物学中一个尚未解决的主要问题是，为什么植物种群经常保持两种繁殖策略的混合，即自花受精和异花授粉。长期存在的遗传理论预测，这两种基因很少会共存。然而，这种双重策略在自然界中出奇地普遍，这表明现有的理论是不充分的。该项目验证了植物物种之间的生态相互作用有助于维持双重策略的假设。当多种植物一起开花并共享传粉者时，花粉往往浪费在其他物种的花上，从而降低了异花授粉的好处。研究人员将通过结合理论发展、传粉者行为的实地研究和亲子关系的分子遗传学研究来评估这一假设。这项研究将加强对植物和传粉者群落的保护，并将帮助科学家了解入侵物种和栖息地破碎化如何影响传粉。与经济条件较差的K-12学校建立伙伴关系将促进对保护和生物多样性的更好理解。本文将以多年生植物三叶草（Mimulus ringens）为研究对象，从实证和理论两方面探讨传粉者共享如何影响异交传粉与自交传粉的权衡。操纵性实验将评估生态环境的变化是否会影响自然选择对自交的模式，即同花物种半边莲的丰度。对32个共花物种类型和丰度不同的自然种群进行比较，将提供自交率、花粉限制、花形态、近交抑制和进化反应等方面的信息。将使用自适应动力学方法开发模型，该方法将结合自交的自动优势，近亲繁殖抑制的进化变化；它将解释共花物种的存在造成的花粉损失，并将探索可能产生混合交配稳定选择的遗传和生态因素的范围。这些相关的实证和理论研究将为理解植物交配系统的进化提供一个广泛的新框架。

A major unsolved question in biology is why plant populations often maintain a mixture of two reproductive strategies, self-fertilization and cross-pollination. Long standing genetic theories predict that these should rarely co-exist. Yet this dual strategy is surprisingly common in nature, suggesting that existing theory is inadequate. This project tests the hypothesis that ecological interactions among plant species help maintain dual strategies. When multiple plant species flower together and share pollinators, pollen is often wasted on flowers of other species, reducing the benefits of cross-pollination. The researchers will evaluate this hypothesis through a combination of theory development, field studies of pollinator behavior, and molecular genetic studies of parentage. This research will enhance conservation of plant and pollinator communities and will help scientists understand how invasive species and habitat fragmentation influence pollination. A partnership with an economically-disadvantaged K-12 school will foster improved understanding of conservation and biodiversity. Focusing on the perennial plant Mimulus ringens, empirical and theoretical studies will investigate how pollinator sharing affects the tradeoff between outcross siring and selfing. Manipulative experiments will evaluate whether changes in the ecological context, the abundance of a co-flowering species Lobelia siphilitica, influence patterns of natural selection on selfing. Comparisons of 32 natural populations that vary in the type and abundance of co-flowering species will provide information on selfing rates, pollen limitation, floral morphology, and inbreeding depression, and evolutionary responses. Models will be developed using an adaptive dynamics approach that will incorporate the automatic advantage of selfing, evolutionary changes in inbreeding depression; it will account for pollen loss caused by the presence of a co-flowering species, and will explore the range of genetic and ecological factors that could generate stabilizing selection on mixed mating. These linked empirical and theoretical investigations will provide a broad new framework for understanding the evolution of plant mating systems.