SG: The ecological and evolutionary consequences of mutualisms for species range expansion

在春天看到蜜蜂在花丛中飞来飞去，或者看到几种鸟类全年都在吃树上的水果，这是一种常见的景象。虽然这两个事件似乎无关，但一个潜在的现象将它们联系起来：即相互作用的物种彼此受益。在第一种情况下，蜜蜂为花朵运送花粉，从而分散并帮助它们繁殖，而花朵反过来又为蜜蜂提供花蜜。鸟类通过食用果实（对它们有利）和将种子从母体植物中排出来传播种子。这种种子传播有助于树木与后代竞争。物种之间的这种双向积极的相互作用被称为互惠。这个项目的目的是开发一个数学框架，以了解在生态和进化的背景下，互利主义如何影响物种的扩散能力。这项工作的结果将有助于确定什么时候扩散应该演变的物种参与互利共生，以及它如何影响物种的空间传播。研究人员将利用他们的研究成果来促进本科生的研究，在明尼苏达大学实施跨学科的教学模块，并制定管理策略，对共同入侵的互惠物种。虽然存在的理论，如捕食，竞争或寄生的拮抗相互作用如何影响物种的扩散，存在很少的互惠作用。目前的理论提供了关于互惠作用是促进还是阻碍物种向新区域扩散（范围扩张）的对比预测。更根本的是，对于参与互惠共生的物种来说，扩散能力是否以及如何进化还不清楚。因此，这项研究将建立一个数学框架，帮助确定在什么条件下互惠（通过对人口统计和扩散的影响）加速与减缓参与物种的范围扩张。其次，该研究将测试运动在两种微生物物种之间的空间显式互利共生中在进化上有益的条件。这些问题将通过数学模型和严格控制的微生物实验系统的组合来解决。该奖项反映了NSF的法定使命，并被认为值得通过使用基金会的智力价值和更广泛的影响审查标准进行评估来支持。

It is a common sight to see bees flitting around flowers during springtime or see several bird species consuming fruits from trees through the year. Although the two events seem unrelated, an underlying phenomenon connects them: namely, that the interacting species benefit each other. In the first case, the bees transport pollen for the flowers thereby dispersing and aiding them in reproduction, and the flowers in turn provide nectar to the bees. Birds disperse seeds by consuming the fruit (a benefit to them) and defecating the seeds away from the parent plant. This seed dispersal helps trees from competing against their offspring. These bidirectional positive interactions between species are termed mutualisms. The aim of this project is to develop a mathematical framework to understand how mutualisms impact species dispersal ability in an ecological and evolutionary context. The outcome of this work will help to identify when dispersal should evolve for species participating in a mutualism and how it impacts the spatial spread of the species. The researchers will use their results to foster undergraduate research, implement interdisciplinary teaching modules at the University of Minnesota, and develop management strategies against co-invading mutualistic species.Although there exists theory on how antagonistic interactions such as predation, competition, or parasitism impact species dispersal, there exists very little on the role of mutualisms. Current theory offers contrasting predictions on whether mutualisms promote or hinder how fast species can disperse into new areas (range expansion). More fundamentally, it is unclear whether and how dispersal ability should evolve for species participating in a mutualism. This research will therefore set up a mathematical framework that will help determine under what conditions mutualisms (through effects on demography and dispersal) speed up versus slow down range expansion of the participating species. Secondly, the research will test the conditions under which motility is evolutionarily beneficial in a spatially explicit mutualism between two microbial species. These questions will be addressed through a combination of mathematical models and a tightly controlled microbial experimental system.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.