The Ecology & Evolution of Species Range Limits

生态学

• 批准号: RGPIN-2014-06011
• 负责人: Eckert, Christopher
• 金额: $ 5.76万
• 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: 2017
• 资助国家: 加拿大
• 起止时间: 2017-01-01 至 2018-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=632091
• 关键词: Ecology; Evolution; Species; Range; Limits

All organisms are limited in their geographic distribution, but how and why these range limits occur are poorly understood. What ecological processes enforce range limits over the short-term, and what genetic constraints prevent natural selection from enabling range expansion over the long term? This deficiency prevents realistic forecasting of whether species will shift their ranges or go extinct during climate change, and effective conservation strategies for Canadian species at risk, most of which occur in Canada at the northern limits of broader distributions south of the US border. My research seeks a better understanding of the ecology and evolution of range limits.A species’ distribution is thought to reflect its ecological niche: the conditions under which survival and reproduction are sufficient for sustainable populations. Areas where a species does not occur are simply outside of its niche. However, we recently analyzed studies that measured performance of species transplanted beyond their ranges and found that range limits did not coincide with niche limits in > 50% of all cases. Unfortunately, few studies were designed to provide definitive answers, so there is a clear need for more experiments. The dispersal capacity of a species may also constrain its distribution, but this remains speculative. We will combine large-scale geographic surveys, transplant experiments and genetic estimates of dispersal to test the relative contribution of niche limits vs dispersal to range limits.Long-term evolutionary stasis of range limits is thought to arise because range-edge populations lack genetic variation in traits that would allow persistence beyond the limit, or because natural selection for improved performance at the limit is continually thwarted by the immigration of genes from larger populations towards the range centre. We will test these hypotheses by combining transplant experiments and genetic analyses of gene movement and the adaptive potential of edge populations.Geographic range edges may be venues for significant evolution. For instance, some plants show striking range-edge changes in reproduction, often involving a shift from sexuality to asexuality. The loss of sex and thus genetic recombination at the range edge may reduce potential for further adaptation. On the other hand, asexuality can preserve unique combinations of genes advantageous in edge environments from being broken up by recombination. We will evaluate these hypotheses by comparing the performance of transplanted sexual and asexual genotypes in central vs edge habitats as well as testing for the genomic signature of long-term asexuality at range edges.This research will help answer fundamental questions at the forefront of biology and contribute to the conservation of rare species, the management of exotic invaders, and better forecasting of species’ responses to climate change; key environmental problems impinging on Canadian biodiversity. I will work with species proven to be excellent experimental subjects and experimental techniques we have used with success. The proposed research involves a range of highly transferable technical skills including modern genetic techniques, field biology in diverse ecosystems, experimental design, advanced statistical analysis and bioinformatics. As such it will provide trainees at all levels with research experiences and skills suited to their diverse interests and long-term career goals in academia, resource management and industry. Ongoing research partnerships with Parks Canada, Ontario MNR, California State Parks and US Park Service also broaden the scope of training and facilitate the transfer of information and skills between university researchers, government scientists and policy-makers.

所有生物的地理分布都受到限制，但是如何以及为什么发生这些范围限制的理解很少。哪些生态过程在短期内强制执行范围限制，哪些遗传约束可以阻止自然选择长期实现范围扩展？这种缺陷可以防止对物种在气候变化期间是否会改变其范围或灭绝的现实预测，以及对处于危险中的加拿大物种的有效保护策略，其中大多数发生在加拿大的北部北部范围内，位于美国边界以南的广泛分布。我的研究寻求更好地了解范围限制的生态和演变。一种物种的分布被认为反映了其生态位：生存和繁殖足以容纳可持续人群的条件。不发生物种的区域仅在其利基市场之外。但是，我们最近分析了研究，该研究测量了超出其范围的物种的性能，发现范围限制与> 50％的所有情况下的范围限制并不与利基限制相吻合。不幸的是，很少有研究被设计为提供明确的答案，因此明显需要进行更多的实验。物种的分散能力也可能会限制其分布，但这仍然投机。 We will combine large-scale geographic surveys, transplant experiments and genetic estimates of dispersion to test the relative contribution of niche limits vs dispersal to range limits.Long-term evolutionary stages of range limits is thought to arise because range-edge populations lack genetic variation in traits that would allow persistence beyond the limit, or because natural selection for improved performance at the limit is continuously thwarted by the immigration从较大人群到范围中心的基因。我们将通过结合基因运动的移植实验和遗传分析以及边缘种群的适应潜力来检验这些假设。地理范围边缘可能是显着进化的场所。例如，某些植物在繁殖方面表现出惊人的范围边缘变化，通常涉及从性行为转向无性恋。性别的丧失以及在范围边缘处的遗传重组可能会降低进一步适应的潜力。另一方面，无性性可以保留在边缘环境中基因优势的独特组合，以免被重组分解。我们将通过比较中央与边缘栖息地中移植的性和无性基因型的表现以及对范围边缘长期无性无情的基因组签名进行测试来评估这些假设。这项研究将帮助回答生物学最前沿中的基本问题，并为稀有物种的保护，以及对稀有的动物的管理，以及越来越多的物种的管理，以及效率更好的种类，有效果，有效果。危及加拿大生物多样性的关键环境问题。我将与被证明是我们成功使用的出色实验学科和实验技术合作。拟议的研究涉及一系列高度转移的技术技能，包括现代遗传技术，潜水生态系统的现场生物学，实验设计，高级统计分析和生物信息学。因此，它将为受训者提供各种研究经验和技能，这些研究经验和技能适合于其在学术界，资源管理和行业中的多元化兴趣和长期职业目标。与加拿大公园，安大略省，加利福尼亚州立公园和美国公园管理局的正在进行的研究合作伙伴关系也扩大了培训和支持大学研究人员，政府科学家和政策制定者之间信息和技能传递的范围。