Behavioral Dysfunction and the Evolution of Reproductive Isolation between Species

不同物种的繁殖，称为杂交，是一种常见的现象，它提出了一个基本问题：如果物种可以杂交，那么是什么保持了它们的独特特征并使物种保持分离？这个问题的答案通常集中在杂交后代上：如果杂交后代不能生存或繁殖，那么物种之间的基因交换将受到限制，物种将保持分离和独特。到目前为止，大多数研究杂种表现不佳的可能性的工作集中在杂种的生理和形态上。很少有研究调查杂交是否表现出改变的行为，阻止他们繁殖，从而限制进一步的基因交换。拟议的工作评估的影响，行为杂交铲足蟾蜍物种。通过这样做，这项研究将为行为如何帮助维持物种边界提供重要的见解。这项研究对于理解生物多样性和保护可能与其他物种杂交的濒危物种具有重要意义。在开展这项工作时，PI将在研究技术和公共宣传方面对本科生和研究生进行培训。事实上，PI和她的实验室成员将通过在北卡罗来纳州自然科学博物馆的工作，在北卡罗来纳州及其他地区进行公共宣传。具体来说，他们将在博物馆的每日星球剧院，提供现场节目，博物馆游客和现场流媒体演示的K-12学校，老年中心，和图书馆在整个北卡罗来纳州。这些介绍的视频以播客的形式上传到iTunes大学，博物馆在该网站上每月有20 000次下载，并上传到博物馆的网站上，该网站每年有大约100万次点击;通过博物馆网站分发的节目向任何地方的用户提供。它们具有阻止基因在它们之间流动的进化特征。这种“隔离机制”的一个主要类别包括在杂交后代中产生低适应性的特征，从而阻止他们与亲本群体回交。由于杂交适应不良对物种形成过程至关重要，因此澄清杂交适应不良的原因是理解物种形成的核心。 大多数物种形成研究都集中在杂种适应不良的三个原因上：存活率降低，生育率降低，以及在双亲生态位中成功的可能性降低。相比之下，行为在杂种适应不良中的作用，特别是杂种可能表现出功能失调的生殖行为，一直相对研究不足。然而，可行的，可生育的杂交种可能无法适当地响应求偶信号，或者，他们可能会表达配偶偏好，减少他们与健身增强配偶交配的可能性。这种功能失调的生殖行为可能会使可行的，可育的杂种“行为不育”，从而作为一个潜在的关键物种之间的隔离机制。 这项拟议中的工作将确定杂交铲足蟾蜍是否表现出功能失调的生殖行为，以及这种行为是否解释了自然种群中的基因交换模式。使用两种自然杂交的蟾蜍，研究将：1）评估杂交反应的繁殖机会; 2）建立杂交交配偏好; 3）测量交配偏好的适应性后果; 4）确定杂交种是否在繁殖上投资较少; 5）确定田间杂交交配的模式。这些项目将共同确定行为在物种边界的起源和维护中的作用。

The breeding of different species, called hybridization, is a common phenomenon that raises a fundamental problem: if species can interbreed, what maintains their distinct characteristics and keeps species separated? Answers to this question have usually focused on hybrid offspring: if hybrids cannot survive or reproduce, then gene exchange between species will be restricted and species are kept separate and distinct. To date, most work exploring the possibility that hybrids perform poorly focuses on hybrid physiology and morphology. Few studies have investigated whether hybrids show altered behaviors that prevent them from reproducing and thereby limiting further gene exchange. The proposed work evaluates the impact of behavior on hybridization in spadefoot toad species. By doing so, the research will provide important insights into how behavior acts to help maintain species boundaries. The research has critical implications for understanding biodiversity and conservation of endangered species that could hybridize with others. In carrying out this work, the PI will train undergraduates and graduate students in both research techniques and public outreach. Indeed, the PI and her lab members will engage in public outreach in North Carolina and beyond through work at the North Carolina Museum of Natural Sciences. Specifically, they will give talks in the museum's Daily Planet Theater, which provides live programming to museum visitors and live streaming of presentations to K-12 schools, senior centers, and libraries throughout North Carolina. Videos of these presentations are uploaded as podcasts onto iTunes University, on which the museum receives 20,000 downloads a month, and to the museum's website, which receives approximately one million hits per year; programs distributed via the museums website are available to users anywhere.Under the widely used biological species concept, species are defined as groups of organisms that do not exchange genes; they possess evolved features that prevent gene flow between them. A major class of such 'isolating mechanisms' includes traits that engender low fitness in hybrid offspring, thereby preventing them from backcrossing to the parent populations. Because hybrid maladaptation is crucial to the speciation process, clarifying the causes of hybrid maladaptation is central to understanding speciation. Most speciation research has focused on three causes of hybrid maladaptation: decreased survival, reduced fertility, and decreased likelihood of succeeding in either parental niche. In contrast, the role of behavior in hybrid maladaptation, specifically that hybrids might exhibit dysfunctional reproductive behavior, has been relatively understudied. Yet, viable, fertile hybrids might fail to respond appropriately to courtship signals, or, alternatively, they might express mate preferences that reduce their likelihood of mating with fitness-enhancing mates. Such dysfunctional reproductive behavior could render viable, fertile hybrids 'behaviorally sterile', thereby acting as a potentially key isolating mechanism between species. The proposed work will ascertain if hybrid spadefoot toads display dysfunctional reproductive behaviors, and whether such behavior explains patterns of gene exchange in natural populations. Using two species of naturally hybridizing toads, the research will: 1) evaluate hybrid responses to breeding opportunities; 2) establish hybrid mate preferences; 3) measure the fitness consequences of mate preferences; 4) ascertain whether hybrids invest less in reproduction; and 5) determine patterns of hybrid mating in the field. Together, the projects will identify behavior's role in the origins and maintenance of species boundaries.