EAGER: Does Adaptation Facilitate or Constrain Further Adaptation? Evaluating the Origins of Character Displacement.

生物学的一个核心目标是解释生物多样性的起源。达尔文首先提出生物多样性的一个主要原因是竞争。他的观点的核心是，当生物体争夺稀缺资源时，自然选择应该有利于那些最不像竞争对手的个体。因此，自然选择会导致这些个体随着时间的推移变得越来越不相似，可能成为不同的物种。然而，物种之间的竞争不仅仅是为了资源：它们还可以通过干扰彼此识别配偶的能力来竞争。然而，很少有研究评估这两种竞争来源如何相互作用。拟议的工作评估这种可能性使用一种新的模型系统-铲足蟾蜍。这项工作是向前迈出的重要一步，因为拟议的实验将为性状变异的起源及其对适应性进化的影响提供见解。该研究的重点是字符位移，这是一个重要的中心进化和生态概念，了解生物多样性的起源，丰度和分布。这项工作通过在北卡罗来纳州自然科学博物馆的工作，让学生参与北卡罗来纳州及其他地区的公共宣传。性格置换有两种形式：生态性格置换，其中性状响应选择而进化，以最大限度地减少物种之间的资源竞争;生殖性格置换，其中性状响应选择而进化，以最大限度地减少有害的生殖相互作用（例如，杂交）。以往的研究大多集中在生态或生殖的性格位移，但不是两者兼而有之。然而，由于足够相似以竞争资源的物种通常也足够相似以进行生殖互动，这两个过程可能经常相互作用。一个未经检验的假设，两种形式的字符位移如何相互作用的是，一个过程中改变性状变异的方式，无论是促进，或约束，人口的选择在该替代环境。该项目将使用现场和实验室实验来验证这一假设，通过实验模拟“第一次接触”的两个物种的铲足蟾蜍，已经经历了生态和生殖特性相互位移。具体来说，科学家们将评估与一个过程相关的性状差异是否会产生新的性状变异，而另一个过程可能会对这种变异产生影响。在这样做的过程中，这项研究有望产生深远的影响。特别是，由于性格置换是生物多样性的起源，丰度和分布的核心，了解其起源可以揭示进化生物学和生态学中一些最基本的问题，包括多样性的原因，物种共存，群落组装和物种分布。

A central goal of biology is to explain the origins of biodiversity. Darwin first proposed that a major cause of biodiversity is competition. The crux of his idea is that when organisms compete for scarce resources, natural selection should favor those individuals that are least like their competitors. Consequently, selection should cause these individuals to become more dissimilar over time, possibly becoming different species. However, species can compete for more than just resources: they can also compete by interfering with each other's ability to identify mates. Yet, few studies have evaluated how these two sources of competition interact with each other. The proposed work evaluates this possibility using a novel model system - spadefoot toads. The work is a significant step forward because the proposed experiments will provide insights into the origins of trait variation and its effects on adaptive evolution. The research is focused on character displacement which is a central evolutionary and ecological concept important to understanding the origins, abundance, and distribution of biodiversity. The work engages students in public outreach in North Carolina and beyond through work at the North Carolina Museum of Natural Sciences.Character displacement takes two forms: ecological character displacement in which traits evolve in response to selection to minimize resource competition between species; reproductive character displacement in which traits evolve in response to selection to minimize deleterious reproductive interactions (e.g., hybridization) between species. Most previous studies of character displacement have focused on either ecological or reproductive character displacement, but not both. Yet, because species that are similar enough to compete for resources are also often similar enough to interact reproductively, the two processes might often interact. An untested hypothesis for how the two forms of character displacement interact is that one process alters trait variation in the alternative context in a way that either facilitates, or constrains, a population's response to selection in that alternative context. This project will use both field and laboratory experiments to test this hypothesis by experimentally mimicking "first contact" between two species of spadefoot toads that have undergone both ecological and reproductive character displacement with each other. Specifically, the scientists will evaluate whether divergence in traits associated with one process generates novel trait variation on which the alternative process could act. In doing so, the research promises to have far reaching implications. In particular, because character displacement is central in the origins, abundance, and distribution of biodiversity, understanding its origins can shed light onto some of the most fundamental issues in evolutionary biology and ecology, including the causes of diversity, species coexistence, community assembly, and species distributions.