The roles of geographical isolation, secondary contact, and mitonuclear disequilibrium in speciation

地理隔离、次级接触和线粒体核不平衡在物种形成中的作用

• 批准号: RGPIN-2019-04920
• 负责人: Lougheed, Stephen
• 金额: $ 3.42万
• 依托单位: Queen's University
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2021
• 资助国家: 加拿大
• 起止时间: 2021-01-01 至 2022-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=737950
• 关键词: roles; geographical; isolation; secondary; contact

One of the enduring challenges in biology is understanding how new species arise, a challenge that predates Charles Darwin. Although speciation is conceptually simple, involving the evolution of traits that prevent interbreeding of diverged populations, there are key knowledge gaps. For example, why do new sister species often begin as geographically isolated populations and what selective forces cause divergence? What happens when isolated populations come back together, and does this play a role in completing speciation? What genetic changes contribute to the evolution of species? One new idea proposes that proteins encoded by nuclear and mitochondrial genes that perform critical functions (energy production in cells) diverge in among geographically isolated populations, with hybrids between populations having lower fitness because nuclear and mitochondrial encoded proteins do not work well together. Thus a new question for understanding species origins asks if such mitochondrial-nuclear coevolution might cause hybrid disfunction between species. Our proposed NSERC-funded research addresses these questions, focusing on the spring peeper, a small North American treefrog. Previous work reveals a dynamic evolutionary history with 3 nuclear lineages that originated in refugia, and clear zones of secondary contact. We found differences in male advertisement calls and behavior among lineages (calling from the ground or perches). We will use playback experiments to test whether females perceive call differences, and plaster model frogs to assess physiological costs of calling from perches (e.g. evaporative water loss). At 5 known contact zones we will combine genomics, and call analysis and playbacks to evaluate outcomes of contact between previously isolated lineages. We will use functional genomics, physiological, and molecular evolution approaches to test costs of hybridization caused by mismatch between nuclear and mitochondrial encoded proteins. For two congeners of the spring peeper, western and boreal chorus frogs, we will use niche modeling and genomics to test the outcomes of secondary contact, and if interspecific interactions or abiotic factors are more important in shaping species distributions. This research will provide premier training for a minimum of 4 PhD, 3 MSc and >10 BSc students in genomics, quantitative methods, and professional development. This work helps put Canada at the forefront of speciation research, bringing together perspectives from genomics, physiology, biogeography, and spatial ecology. It helps us to understand what factors shape species ranges and how they have shifted in response to past climate change, and can provide inputs into conservation strategies for species at risk; e.g. how best to retain evolutionary potential, and how species' distributions might be affected by climate change. I will also leverage NSERC research to secure other opportunities for conservation studies of Canadian species at risk.

生物学的持久挑战之一是了解新物种是如何出现的，这是查尔斯·达尔文（Charles Darwin）早的挑战。尽管物种在概念上很简单，涉及防止种群杂交的性状的演变，但存在关键的知识差距。例如，为什么新姐妹物种通常以地理孤立的种群开始，而哪些选择性力量会引起分歧？当孤立的种群重新融合在一起时会发生什么？哪些遗传变化有助于物种的进化？一个新想法提出，由核和线粒体基因编码的蛋白质在地理分离的种群之间发挥关键功能（细胞中的能量产生），由于核和线粒体编码的蛋白质的杂种在较低的健身性群体之间存在杂种。因此，理解物种起源的一​​个新问题询问这种线粒体核共核是否可能导致物种之间的混合功能。 我们提议的NSERC资助研究解决了这些问题，重点是苏格里冰气，这是一个小型北美树蛙。先前的工作揭示了动态的进化史，其中有3个起源于Refugia的核谱系和次要接触的清晰区域。我们发现谱系中男性广告的呼叫和行为（从地面或栖息处呼叫）之间存在差异。我们将使用播放实验来测试女性是否会感知呼叫差异和石膏模型青蛙来评估鲈鱼呼叫的生理成本（例如蒸发性水损失）。在5个已知的接触区域，我们将结合基因组学，并调用分析和播放来评估先前隔离的谱系之间的接触结果。我们将使用功能基因组学，生理和分子进化方法来测试由核和线粒体编码蛋白之间错配的杂交成本。对于春季窥视者，西方和北方合唱青蛙的两个同类物，我们将使用利基建模和基因组学来测试次级接触的结果，如果种间相互作用或非生物因素在塑造物种分布方面更为重要。这项研究将提供至少4个博士学位，3个MSC和> 10个BSC学生的基因组学，定量方法和专业发展的主要培训。这项工作有助于将加拿大置于形成研究的最前沿，从而汇集了基因组学，生理学，生物地理学和空间生态学的观点。它有助于我们了解哪些因素塑造物种范围以及它们如何响应过去的气候变化，并可以为处于危险中的物种的保护策略提供投入；例如如何最好地保留进化潜力，以及物种分布如何受到气候变化的影响。我还将利用NSERC研究来确保对有风险的加拿大物种的保护研究。