Key drivers and functional significance of sensory and behavioral trait divergence across multiple environmental stressors in an African cichlid

人类密切依赖地球有限的淡水资源，但由于水质退化，却极大地改变了水生系统。尽管这导致了许多淡水鱼物种的灭绝，但一些鱼类物种能够应付并生存下来，尽管环境发生了迅速和严重的变化。为了预测和遏制更多的物种灭绝，迫切需要发现哪些特征可能会让一些物种在另一些物种灭绝的情况下继续存在。该项目旨在确定鱼类如何在变化的环境条件下适应和坚持；例如，通过询问如果由于砍伐森林的斜坡泥泞的径流而导致水的清晰度降低，鱼类如何寻找配偶和繁殖。为了实现这一目标，该项目将研究乌干达一种广泛分布的热带淡水鱼的反应，这种鱼在农业和砍伐森林等人类活动导致水透明度和氧气供应下降的条件下持续存在。这项研究结合了对野生捕获的鱼的调查，这些鱼在自然系统的内在变化中发育和生活，并在实验室进行了对照实验。这种方法提供了一个独特的机会，可以梳理出那些允许这种鱼类在一系列环境压力下生存和繁殖的特征。水质退化对鱼类和人类的影响是全球关注的问题；因此，该项目还旨在通过水质教育和虚拟交流计划在乌干达和俄亥俄州的青年之间建立联系。尽管人类引起的快速环境变化(HIREC)经常导致生物多样性丧失，但一些物种能够通过表型可塑性和/或遗传进化来应对多种环境压力。响应HIREC的表型变化已经在广泛的分类群中被记录下来；然而，我们对表型变化何时是适应性的并促进种群持久性，或者何时是不适应的并导致种群下降的了解很少。拟议的项目将基于广泛的试点数据解决中心假设，即由多种环境应激源(如低氧和浑浊)驱动的表型变化在功能上是显著的，并且这些特征差异在应激源的自然组合下赋予健康优势。具体地说，目标是通过确定(1)性状变化的功能意义，以及(2)性状变化赋予适应优势的机制，将HIREC驱动的表型变化与性状变化的适应价值联系起来。这将通过利用在经历极端多种环境应激源的非洲慈鱼种群中与繁殖相关的感觉和行为特征的已知差异来实现。提出的方法将通过将个体表型与世代适应度具体联系起来，促进我们对人类影响的水生生态系统表型变化的关键驱动因素和功能意义的理解。更广泛地说，这样的理解将使人们能够预测物种的持久性和减轻HIREC下的生物多样性丧失。

Humans rely intimately on Earth's limited freshwater resources but have disproportionately altered aquatic systems through degradation of water quality. Although this has led to the extinction of many freshwater fish species, some fish species are able to cope and persist despite rapid and severe changes in the environment. In order to predict and curb additional extinctions, there is a critical need to discover what traits might allow some species to persist while others go extinct. This project aims to identify how fish adapt and persist under altered environmental conditions; for example, by asking how fish find mates and reproduce if water clarity is reduced due to muddy run-off from deforested slopes. To accomplish this goal, this project will examine the responses of a wide-spread tropical freshwater fish in Uganda that has persisted under conditions of decreased water clarity and oxygen availability resulting from human activities such as agriculture and deforestation. The study combines surveys of wild-caught fish that develop and live under the inherent variation in natural systems with controlled experiments in the laboratory. This approach provides a unique opportunity to tease apart those traits that allow this fish species to survive and reproduce across a range of environmental stressors. The influence of degraded water quality on fish and humans is of global concern; therefore, this project also aims to create connections between youth in Uganda and in Ohio through a water quality education and virtual exchange program.Although human-induced rapid environmental change (HIREC) often leads to biodiversity loss, some species are able to cope with multiple environmental stressors through phenotypic plasticity and/or genetic evolution. Phenotypic change in response to HIREC has been documented in a broad array of taxa; however, we understand very little about when phenotypic change is adaptive and promotes population persistence or is maladaptive and leads to population decline. The proposed project will address the central hypothesis, based on extensive pilot data, that phenotypic changes driven by multiple environmental stressors (e.g. hypoxia and turbidity) are functionally significant and that these trait differences confer fitness advantages under naturally occurring combinations of the stressors. Specifically, the goal is to link HIREC-driven phenotypic change with the adaptive value of trait changes, by determining (1) the functional significance of trait changes, and, (2) the mechanisms by which trait changes confer a fitness advantage. This will be accomplished by taking advantage of known divergence in sensory and behavior traits associated with reproduction in populations of an African cichlid fish experiencing extremes of multiple environmental stressors. The approach proposed will advance our understanding of the key drivers and functional significance of phenotypic change in human-impacted aquatic ecosystems by specifically linking individual phenotype with fitness across generations. More broadly, such understanding will allow predictions to be made about species persistence and mitigation of biodiversity loss under HIREC.