Roles of isolation, secondary contact and gene flow in diversification and speciation.

隔离、二次接触和基因流在多样化和物种形成中的作用。

• 批准号: RGPIN-2014-06150
• 负责人: Lougheed, Stephen
• 金额: $ 3.06万
• 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: 2016
• 资助国家: 加拿大
• 起止时间: 2016-01-01 至 2017-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=612058
• 关键词: Roles; isolation; secondary; contact; gene

One of the most enduring goals in evolutionary biology is to understand how new species arise. The traditional view, popularized by 20th Century evolutionary biologist Ernst Mayr, emphasized a geographic view of speciation where most new species arise or at least begin through physical and thus genetic isolation of ancestral populations. Recent theoretical and empirical work has moved away from these geography-based views of speciation to ones that emphasize mechanism (e.g. selection driving ecological divergence) producing important insights into how new species arise. However, our own NSERC-funded research over the last 5 years highlights the pervasiveness of both geographic isolation and subsequent secondary contact in the histories of most vertebrate species, mirroring comprehensive reviews of the phylogeographic literature. Thus, the long-term objective of my NSERC-funded research over the next 5 years is to quantify the role of such long-term geographical isolation, and consequences of range dynamics, and especially secondary contact in the evolution and maintenance of species. My proposed NSERC research focuses on a single temperate eastern North American frog, the spring peeper (Pseudacris crucifer), which I am developing into a model system for speciation studies. Our published work suggests that the spring peeper has a dynamic evolutionary history with 6 well-supported evolutionary lineages that originated in distinct, isolated refugia between 11 and 3 million years before present. Different lineage pairs with disparate times of divergence have come into secondary contact in different parts of the species’ range, presumably within the last 10-15,000 years. In the proposed research, my students and I will combine large-scale genomic and geographic information system (GIS) data, new statistical and modeling techniques, bioacoustical analysis, and playback and hybridization experiments to address a series of research questions on speciation: (i) What is the relation of divergence times between evolutionary lineages and patterns of reproductive isolation, the hallmark of biological species? (ii) What do genomic data say about the patterns of gene flow among lineages over the entire history of this species? (iii) Does secondary contact of closely-related lineages result in more effective reproductive barriers, either to diminish acoustic interference of male advertisement calls (used by females in mate choice), or to prevent maladaptive hybridization? (iv) How might marked differences in the acoustic environment or seasonality shape the outcomes of secondary contact between diverging lineages? (v) What are the various fitness costs of hybridization between lineages? My research program helps put Canada at the forefront of speciation research, bringing together perspectives from biogeography, genomics, landscape ecology, and ecological genetics. It provides important inputs into conservation strategies for Canadian species at risk, for example how best to retain evolutionary potential for future diversification and adaptation, and whether phylogeographic divisions merit separate conservation designation. The training program that I outline will provide premier opportunities for a minimum of 4 PhD, 3 MSc and 25 BSc students in genetics, quantitative methods, GIS, and professional development. As I have done in the past, I will leverage expertise developed with my NSERC research to seek additional funding and opportunities for applied landscape genetic & conservation studies of Canadian species at risk.

进化生物学最持久的目标之一是了解新物种是如何产生的。由 20 世纪进化生物学家恩斯特·迈尔 (Ernst Mayr) 推广的传统观点强调物种形成的地理观点，即大多数新物种的出现或至少是通过对祖先种群的物理隔离和遗传隔离而产生的。最近的理论和实证工作已经从这些基于地理的物种形成观点转向强调机制（例如选择驱动生态分歧）的观点，从而对新物种如何出现产生重要见解。然而，我们在过去 5 年中由 NSERC 资助的研究强调了大多数脊椎动物物种历史中普遍存在的地理隔离和随后的二次接触，这反映了对系统发育地理学文献的全面回顾。因此，我在未来 5 年由 NSERC 资助的研究的长期目标是量化这种长期地理隔离的作用以及范围动态的后果，特别是物种进化和维持中的二次接触。 我提议的 NSERC 研究重点是北美东部温带青蛙——春蛙（Pseudacris crucifer），我正在将其开发为物种形成研究的模型系统。我们发表的研究表明，春窥鸟有着动态的进化历史，有 6 个得到充分支持的进化谱系，这些谱系起源于距今 11 至 300 万年前的独特、孤立的避难所。具有不同分化时间的不同谱系对在该物种分布范围的不同部分进行了二次接触，大概是在过去 10-15,000 年之内。在拟议的研究中，我和我的学生将结合大规模基因组和地理信息系统（GIS）数据、新的统计和建模技术、生物声学分析以及回放和杂交实验来解决一系列有关物种形成的研究问题：（i）进化谱系与生殖隔离模式（生物物种的标志）之间的分歧时间有何关系？ (ii) 基因组数据对于该物种整个历史中谱系间的基因流动模式有何说明？ (iii) 密切相关的谱系的二次接触是否会导致更有效的生殖障碍，要么是为了减少雄性广告叫声（雌性在择偶时使用）的声音干扰，要么是为了防止适应不良的杂交？ (iv) 声学环境或季节性的显着差异如何影响不同谱系之间二次接触的结果？ (v) 谱系间杂交的各种适应度成本是多少？ 我的研究项目汇集了生物地理学、基因组学、景观生态学和生态遗传学的观点，帮助加拿大处于物种形成研究的前沿。它为加拿大面临风险的物种的保护策略提供了重要的投入，例如如何最好地保留未来多样化和适应的进化潜力，以及系统发育地理划分是否值得单独指定保护。我概述的培训计划将为至少 4 名博士生、3 名硕士生和 25 名理学士学生提供遗传学、定量方法、GIS 和专业发展方面的优质机会。正如我过去所做的那样，我将利用我在 NSERC 研究中积累的专业知识，为加拿大濒危物种的应用景观遗传和保护研究寻求额外的资金和机会。