Differential Adaptation to Plant Toxins: The role of Chemically-mediated Selection in Reproductive Isolation between Mammalian Herbivores.

对植物毒素的差异适应：化学介导的选择在哺乳动物草食动物生殖隔离中的作用。

• 批准号: 1457209
• 负责人: Marjorie Matocq
• 金额: $ 64.68万
• 依托单位: Board of Regents, NSHE, obo University of Nevada, Reno
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2015
• 资助国家: 美国
• 起止时间: 2015-05-15 至 2021-04-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1457209&HistoricalAwards=false
• 关键词: Differential; Adaptation; Plant; Toxins; role

One of the most fundamental ways that an animal interacts with its environment is through its diet. Woodrats (or packrats) are known to specialize on particularly toxic food plants in the wild. This project tests the hypothesis that woodrats overcome certain plant toxins in their diet through a combination of liver detoxification enzymes (biochemical catalysts) as well as through the activity of their gut microbes. The hypothesis will be tested in a natural setting where two species of woodrats come into contact with each other at a sharp habitat transition. Each species is primarily found in one habitat or the other, and appears to specialize on habitat-specific toxic plants. The project will examine whether each species is uniquely adapted to the plant toxins in their native habitat such that they would not be able to sustain themselves on the diet available in the adjacent habitat. As such, these chemically-mediated ecological adaptations may limit genetic exchange, or hybridization, between the species and play an important role in maintaining their distinction. These results will therefore expand understanding of biodiversity and its management in nature. For herbivores, plant chemicals found in most of their food items affect growth, health, and response to changes in diet. Thus, this research will have relevance to production, improvement, and safety of mammalian animals used as food by humans. This research will provide training for numerous students and will allow expansion of a current high school education program wherein teachers and their students participate in a week-long, hands on program focused on the genetic basis of sensitivity in humans to the taste of particular chemicals.This research aims to identify the mechanisms underlying genotype-phenotype-environment interactions across a mammalian hybrid zone that spans a sharp ecological boundary. The system entails two species of woodrat (Neotoma) that hybridize across a sharp ecological transition but occupy distinct habitats and maintain habitat-specific diets with distinct toxin profiles. Woodrats often specialize on highly toxic food plants, but exposure to novel plant toxins generates severe metabolic costs. The hypothesis tested is that diet specialization and the cost of habitat/diet switching is the primary selective force underlying the strong genotype-phenotype-environment relationship in the woodrat system. Further, because strong selection against hybrids during early stages of life, when individuals are transitioning to a plant-based diet, has been demonstrated previously, another hypothesis to be tested is that many hybrids may not be capable of metabolizing either parental diet. To test these hypotheses, field studies and laboratory experiments will be integrated to quantify the pattern (metabolomics, Aim 1), mechanisms (gene expression and gut microbiome, Aim 2), and ecologically-relevant outcome (performance, Aim 3) of diet-mediated selection. Exposure of various genotypic classes (i.e. pure and hybrid woodrats) to habitat-specific diets will be experimentally manipulated to establish patterns of metabolic processing of these diets, identify the underlying liver gene expression and gut microbial community profiles associated with exposure to these diets, and quantify the energetic costs associated with consumption of these diets. The ecological and evolutionary principles associated with this research in diet-based ecological adaptation will be translated to augment current high school outreach programs that focus on the genetic basis of sensitivity in humans to the taste of particular chemicals.

动物与环境相互作用的最基本方式之一是通过饮食。众所周知，森林鼠（或背包鼠）专门研究野外特别有毒的食用植物。该项目测试了一种假设，即林鼠通过肝脏解毒酶（生化催化剂）的组合以及肠道微生物的活性来克服饮食中的某些植物毒素。该假设将在自然环境中进行测试，其中两种林鼠在急剧的栖息地过渡中相互接触。 每个物种主要存在于一个或另一个栖息地，似乎专门研究特定栖息地的有毒植物。该项目将研究每个物种是否对原生栖息地的植物毒素具有独特的适应性，以至于它们无法依靠邻近栖息地的食物维持自己的生命。 因此，这些化学介导的生态适应可能会限制物种之间的遗传交换或杂交，并在保持其独特性方面发挥重要作用。 因此，这些结果将扩大对生物多样性及其自然管理的理解。对于食草动物来说，在大多数食物中发现的植物化学物质会影响生长，健康和对饮食变化的反应。因此，这项研究将与人类用作食物的哺乳动物的生产、改良和安全相关。这项研究将为众多的学生提供培训，并将允许目前的高中教育计划，其中教师和他们的学生参加为期一周的，动手程序集中在人类的敏感性的遗传基础上的特定chemicals.This研究的味道扩大旨在确定潜在的机制基因型-表型-环境的相互作用跨越一个哺乳动物杂交区，跨越一个尖锐的生态边界。该系统需要两个物种的woodrat（Neotoma）杂交跨越一个尖锐的生态过渡，但占据不同的栖息地，并保持特定于栖息地的饮食与不同的毒素配置文件。Woodrats通常专门研究剧毒的食用植物，但接触新型植物毒素会产生严重的代谢成本。检验的假设是，饮食专业化和栖息地/饮食转换的成本是主要的选择力的强大的基因型-表型-环境的关系，在林鼠系统。此外，由于在生命的早期阶段，当个体过渡到以植物为基础的饮食时，对杂交种的强选择已经被证明，另一个有待检验的假设是，许多杂交种可能无法代谢任何亲本饮食。为了验证这些假设，将整合田间研究和实验室实验，以量化饮食介导的选择的模式（代谢组学，目标1），机制（基因表达和肠道微生物组，目标2）和生态相关结果（性能，目标3）。暴露于不同的基因型类（即纯和杂交woodrats）的栖息地特定的饮食将实验操作，以建立这些饮食的代谢处理模式，确定潜在的肝脏基因表达和肠道微生物群落与暴露于这些饮食，并量化与这些饮食的消费相关的能量成本。与这项基于饮食的生态适应研究相关的生态和进化原则将被转化为加强目前的高中外展计划，该计划专注于人类对特定化学品味道敏感性的遗传基础。