BEE: The Evolution of Fluctuation-Dependent Species Coexistence

自生态学诞生以来，了解相似物种如何共存一直是生态学的中心问题。这个问题很重要，因为物种多样性是自然生态系统的一个决定性特征。这个问题的传统答案集中在物种在不变的环境中所使用的资源类型有何不同。在这一范式下，当进化使物种在资源利用上不那么相似时，它可以促进物种共存。然而，自然生态系统并不是一成不变的，最近人们对了解环境中的时间变化以及物种对这种变化的反应方式的差异如何导致有利于共存的条件感兴趣。虽然我们在理论上知道这些波动依赖的机制，但我们对它们是否能促进自然种群中的物种共存知之甚少。我们对进化如何促进或阻碍这种波动依赖的机制所知更少。这项研究通过利用自然界中的实验进化研究以及数学模型和人工溪流中的实验来解决这些问题。这项研究每年将有38名来自不同背景的青年科学家参加青年科学家培训计划。青年科学家获得了研究经验，并辅以生态学、进化论和统计学方面的培训。研究人员还将通过一个在线外展网站吸引公众参与，并将通过手机游戏、社交媒体和基于该系统的教师培训模块开发生态和进化方面的培训。这项工作将对自然群落中依赖波动的共存机制进行多管齐下的测试，并调查它们是如何演变的。通过这样做，这项工作将综合生态学和进化生物学的想法。这项研究利用了西印度群岛特立尼达溪流群落结构提供的自然实验室，那里的鱼类群落由特立尼达孔雀鱼和哈特鱼或哈特鱼本身组成。孔雀鱼-孔雀鱼群落是当孔雀鱼入侵只有剑鱼的社区时形成的。先前的研究表明，在这些入侵之后，孔雀鱼和剑鱼在它们的生活史和资源使用上迅速进化出不同之处。这些溪流也是季节性很强的，有明显的旱季和湿季。剑鱼和孔雀鱼对这些季节性波动的反应是否不同？孔雀鱼是否适应旱季条件，鲤鱼是否适应雨季条件？如果是这样，那么这种差异为这两个物种的共存提供了一条途径。这项研究还将探讨这些波动依赖机制相对于传统的波动独立机制的重要性，并确定这些贡献如何通过社区的形成而变化。这项研究将利用自然生态系统中重复的实验进化研究，包括结构化模型、人工溪流中的因子实验和稳定的同位素工作。同时，数学模型将提供一个框架，将物种共存理论与进化理论联系起来。这一奖项反映了NSF的法定使命，并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，被认为值得支持。

Understanding how similar species coexist has been a central question in ecology since its inception. The question is important because species diversity is a defining characteristic of natural ecosystems. Traditional answers to this question focus on how species differ in the types of resources they use in non-fluctuating environments. Under this paradigm, evolution can facilitate species coexistence when it makes species less similar in their resource use. However, natural ecosystems are not constant, and there has been recent interest in understanding how temporal variation in the environment, and differences in how species respond to this variation, can lead to conditions that favor coexistence. While we know about these fluctuation-dependent mechanisms in theory, we know little about whether they can promote species coexistence in natural populations. We know even less about how evolution either facilitates or impedes such fluctuation-dependent mechanisms. This research attacks these questions by leveraging studies of experimental evolution in nature together with mathematical models and experiments in artificial streams. The research will engage 38 young scientists from diverse backgrounds per year in the Young Scientist Training Program. The Young Scientists gain research experience that is complemented by training in ecology, evolution, and statistics. The researchers will also engage the public through an online outreach website and will develop training in ecology and evolution through mobile gaming, social media, and teacher training modules based on this system.This work will provide a multipronged test of fluctuation-dependent coexistence mechanisms in natural communities and investigate how they evolve. In doing so, this work will synthesize ideas in ecology and evolutionary biology. This research takes advantage of the natural laboratory provided by the structure of stream communities in Trinidad, West Indies where fish communities consist of either Trinidadian guppies and Hart’s killifish or Hart’s killifish by themselves. Killifish-guppy communities are formed when guppies invade communities with only killifish. Prior research has shown that following these invasions, guppies and killifish rapidly evolve differences in their life histories and resource use. These streams are also highly seasonal with pronounced dry and wet seasons. Do killifish and guppies respond differently to these seasonal fluctuations? Are guppies adapted to dry season conditions and killifish to wet season conditions? If so, then this difference provides an avenue for the two species to coexist. This research will also address how important these fluctuation-dependent mechanisms are relative to traditional fluctuation-independent mechanisms and identify how these contributions change through the formation of the community. This research will leverage replicated experimental evolution studies in natural ecosystems with structured models, factorial experiments in artificial streams, and stable isotope work. At the same time, the mathematical models will provide a framework for linking theory on species coexistence with evolutionary theory.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.