Adaptive decoupling in the evolution of complex life-histories

所有的生物都会随着时间的推移而变化和生长。其中一些变化比其他变化更具戏剧性。两栖动物(如青蛙和火蜥蜴)在发育过程中经历的变化是所有脊椎动物中最戏剧性的。变态是两栖动物从生活在水下的动物转变为生活在陆地上的动物的过程。这种令人难以置信的转变包括重新组织几乎整个动物的身体计划。许多种类的两栖动物会吸收尾巴，长出腿来在陆地上活动，当它们开始呼吸空气时，它们的外部鳃就会消失。所有这些惊人的变化都由一组基因控制。该项目将探索自然选择塑造两栖动物基因组的各种方式，以构建这两种具有相同基因集的截然不同的动物身体。以林蛙为研究系统，研究人员将探索不同环境因素对蝌蚪和成年青蛙发育的影响。通过这样做，这项研究将确定环境与基因表达如何相互作用，以影响林蛙的生存和交配成功。变形是一个令人着迷的观看过程，为不同年龄层次的人提供了学习的机会。研究人员将包括小学生、高中生以及研究生和本科生参与研究。最终，这个项目将对理解自然选择如何影响基因和基因组，使动物能够很好地适应多种环境做出重要贡献。生活史进化研究的一个中心问题是了解权衡如何在构建自然种群中发挥作用。这个项目调查了林蛙在不同的生活阶段(例如，蝌蚪和成蛙)表达的特征之间的潜在权衡。例如，在无尾两栖动物的生活史上可能会出现权衡，因为它们复杂的生活史需要截然不同的适应形式，以适应变态后生态、形态和行为的变化。然而，如果遗传相关性在变态过程中被打破(所谓的“适应-脱钩”)，或者如果特征在整个生活史中受到类似形式的自然选择，这种权衡可能会得到缓解。尽管适应脱钩的想法并不新鲜，但令人惊讶的是，我们仍然对无尾两栖动物生活阶段的耦合程度以及这可能如何影响每个生活阶段的适应能力知之甚少。这个项目将使用半自然中围体(蝌蚪)和野外围栏(青蛙)的组合来测试蝌蚪和青蛙之间自然选择形式的差异。适应性脱钩的程度将使用半同胞育种设计来衡量，以量化生命阶段内和生命阶段之间的遗传相关性。对捕食强度和时间不同的自然种群的实地调查(例如，幼虫和/或成虫阶段的捕食)将检验自然选择和适应-脱钩相互作用影响局部适应的预测。此外，研究人员将测试基因表达的变化和自然选择是否相互作用，影响对交配成功至关重要的特征。

All living things change and grow through time. Some of these changes are more dramatic than others. The changes that amphibians (e.g., frogs and salamanders) undergo during development are some of the most dramatic of any of the vertebrates. Metamorphosis is the process by which an amphibian transforms from an animal that lives under water, to one that lives on land. This incredible transition involves reorganizing almost the entire animal's body plan. Many species of amphibians absorb their tails, grow legs for moving on land, and their external gills disappear as they begin breathing air. All of these amazing changes are controlled by a single set of genes. This project will explore the various ways that natural selection has sculpted the amphibian genome to build these two vastly different types of animal bodies with the same sets of genes. Using the wood frog (Rana sylvatica) as a study system, the researchers will explore the role of different environmental factors that can influence the development of both tadpoles and adult frogs. In doing so, the research will determine how the environment interacts with gene expression to influence survival and mating success of wood frogs. Metamorphosis is a fascinating process to watch and provides opportunities for study at multiple age levels. The researchers will involve elementary school students, high school students, and both graduate and undergraduate researchers in the studies. Ultimately, this project will make important contributions to understanding how natural selection influences genes and genomes to make animals that are well suited to multiple environments.A central problem in the study of life history evolution is to understand how tradeoffs play a role in structuring natural populations. This project investigates potential tradeoffs between traits expressed during alternative life stages (i.e., tadpoles versus adults) in wood frogs, Rana sylvatica. For example, tradeoffs may arise across the life history of anurans because their complex life history requires dramatically different forms of adaptation to match changes in ecology, morphology, and behavior following metamorphosis. However, such tradeoffs could be alleviated if genetic correlations are broken apart during metamorphosis (so called "adaptive-decoupling"), or if traits are subject to similar forms of natural selection throughout the life history. Although the idea of adaptive-decoupling is not new, we still understand surprisingly little about the degree to which anuran life-stages are coupled and how this might influence adaptation in each life stage. This project will test for differences in the forms of natural selection between tadpoles and frogs using a combination of semi-natural mesocosms (tadpoles) and field enclosures (frogs). The degree of adaptive-decoupling will be measured using a half-sib breeding design to quantify genetic correlations within and between life-stages. Field surveys of natural populations that vary in predation intensity and timing (e.g., predation at larval and/or adult life stages) will test the prediction that natural selection and adaptive-decoupling interact to influence local adaptation. Further, the researchers will test whether shifts in gene expression and natural selection interact to influence traits important for mating success.