The Paradox of Coexistence: The Evolution of Ontogenetic Interactions

当两个物种都对另一个物种产生负面影响时，两个物种如何共存？当一个新物种入侵一个栖息地时，我们如何预测它是否会与本土物种共存，导致其中一个或多个物种灭绝，或者被本土物种驱使灭绝呢？这项研究将调查共存是否是物种相互作用的进化属性。如果第一次接触时不能共存的物种能够以一种使它们能够迅速进化到共存的方式，在彼此的特征上扮演自然选择的代理人，这种情况就会发生。了解这种进化发生的时间和方式可以对我们预测入侵、物种补充和栖息地改变对生物多样性的结果产生深远的影响。这项研究将邀请本科生研究人员参与，并通过一个扩展网站吸引公众。这项研究专注于最具挑战性的物种互动之一，即两个物种的成虫相互竞争食物，但每个物种都捕食对方的幼虫。这项研究将研究哈特的剑鱼和特里尼达斯孔雀鱼如何以这种方式相互作用，在特立尼达的高海拔溪流中以某种方式共存。通常情况下，当孔雀鱼入侵那些只有龙鱼的地方时，孔雀鱼就会遇到龙鱼。这项研究利用了这样一个事实，即可以在与孔雀鱼共存的金枪鱼种群和从未见过孔雀鱼的种群之间进行比较，以及在没有入侵仅有金枪鱼的地点的孔雀鱼种群、在最近的实验中引入这些地点的种群以及几十年来与金枪鱼共存的种群之间进行比较。这项工作包括在人工溪流中对这些种群进行混合和匹配，以检验每个物种的适合度如何取决于其自身遗传背景和其他物种的遗传背景的组合。它还包括在自然池塘中进行的实验，将一个物种移出，以衡量其对另一个物种的净影响。研究人员还将在实验介绍中记录孔雀鱼和剑鱼的命运，以评估实际发生了多少进化。还将进行实验室实验，在物种内部和物种之间配对不同体型的个体，以了解竞争和捕食如何依赖于相互作用的个体的相对体型。最后，这项研究将把这些结果与描述生态和进化轨迹的计算模型综合起来，这些模型可以用作了解各种背景下生物多样性命运的工具。

How do two species coexist when each has a negative impact on the other? When a new species invades a habitat, how can we predict whether it will coexist with the native species, drive one or more of them extinct, or be driven to extinction itself by the natives? This research will investigate whether coexistence is an evolved property of species interactions. This will happen if species that could not coexist on first contact can act as agents of natural selection on each other's features in a way that enables them to evolve rapidly to coexist. Understanding when and how this evolution occurs can have a profound effect on our ability to predict the results of invasions, species re-stocking, and habitat alteration on biodiversity. This research will engage undergraduate researchers, as well as engaging the public with an outreach website.This research focuses on one of the most challenging of species interactions, which occurs when the adults of two species compete with each other for food but each preys on juveniles of the other. This research will examine how Hart's killifish and Trinidadian guppies, which interact in this manner, somehow coexist in higher elevation streams in Trinidad. Typically, guppies encounter killifish when guppies invade locations that have held only killifish. This research exploits the fact that comparisons can be made among killifish populations that coexist with guppies and populations that have never encountered guppies, along with comparisons between guppy populations that have not invaded killifish-only locations, populations that have been introduced into those locations in recent experiments, and populations that have coexisted with killifish for decades. The work includes experiments in artificial streams that mix and match these populations to examine how fitness of each species depends on the combinations of its own genetic background and that of the other species. It also includes experiments in natural pools that remove one species to measure its net effect on the other. The researchers will also be documenting the fates of guppies and killifish in experimental introductions to assess how much evolution is actually occurring. There will also be laboratory experiments that pair individuals of different body sizes within and among species to understand how competition and predation depend on relative body sizes of interacting individuals. Finally, the research will synthesize these results with computational models that describe the ecological and evolutionary trajectories, which can be used as tools for understanding the fate of biodiversity in a variety of contexts.