Geographic range limits and adaptation to changing climates: the effects of phenotypic lag, selection, and genetic variance

地理范围限制和对气候变化的适应：表型滞后、选择和遗传变异的影响

• 批准号: RGPIN-2022-04863
• 负责人: Bontrager, Megan
• 金额: $ 2.11万
• 依托单位: University of Toronto
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2022
• 资助国家: 加拿大
• 起止时间: 2022-01-01 至 2023-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=751437
• 关键词: Geographic; range; limits; adaptation; changing

Every species has a limited geographic distribution. In other words, every species occupies a finite area on the landscape. Evolution has allowed life on earth to take many forms and occupy many habitats, so what prevents any particular species from adapting to areas outside their range and spreading indefinitely? As the climate changes, what new evolutionary challenges will populations face, and how will these affect their geographic distributions? These questions are central to research in my lab. In the work proposed here we will test several hypotheses for what constrains adaptation at range edges and under climate change, using an annual wildflower that grows in western North America as our focal species. One possibility is that range limits arise because populations fail to evolve the traits necessary to thrive at and beyond the range edge. If this is the case, we expect phenotypes to deviate further from the optimum near range edges than they do at the range centre. We also expect selection to be strong and directional at the range edge, but weak and stabilizing at the range centre. However, these patterns are rarely measured across geographic ranges. I propose to characterize them in the range centre, at the northern range edge, and beyond, with greenhouse crosses and field transplant experiments in Clarkia pulchella. An additional hypothesis for why range edges occur is that populations at range edges lack the genetic variance in key traits that is necessary to adapt. However, fitness depends upon more traits than can be measured, so I propose to directly measure genetic variance in fitness, again using greenhouse crosses and transplant experiments. My proposed design will allow us to decouple the contributions of population qualities (edge vs. centre) from site qualities (edge vs. centre). We will also examine whether populations are able to adapt to new combinations of environmental factors that they are likely to experience under climate change, or whether genetic correlations constrain the evolution of novel combinations of traits. This type of research is fundamentally interesting, but also important to society. Species of economic and cultural importance are experiencing the effects of climate change. By understanding what has limited distributions in the recent past and what is likely to be limiting in the future, we will be better able to plan conservation and cultivation of important species.

每个物种都有一个有限的地理分布。换句话说，每一个物种在景观中占据有限的区域。进化使地球上的生命有了多种形式，占据了许多栖息地，那么是什么阻止了任何特定的物种适应其范围之外的地区并无限期地传播呢？随着气候变化，种群将面临哪些新的进化挑战，这些挑战将如何影响它们的地理分布？这些问题是我实验室研究的核心。在这里提出的工作中，我们将测试几个假设是什么限制适应范围的边缘和气候变化下，使用一年生野花，生长在北美西部作为我们的焦点物种。 一种可能性是，范围限制的出现是因为种群未能进化出在范围边缘和范围边缘之外茁壮成长所必需的特征。如果是这种情况，我们预计表型偏离最佳近范围边缘比他们在范围中心。我们还预计，在范围边缘，选择是强有力的和有方向的，但在范围中心，选择是弱有力的和稳定的。然而，这些模式很少在不同的地理范围内进行衡量。我建议他们的特点是在范围中心，在北方范围的边缘，并超越，温室十字架和田间移植实验Clarkia pulchella。 另一个关于为什么会出现范围边缘的假设是，范围边缘的种群缺乏适应所必需的关键性状的遗传变异。然而，健身取决于更多的性状比可以测量，所以我建议直接测量健身的遗传方差，再次使用温室杂交和移植实验。我提出的设计将使我们能够解耦的人口素质（边缘与中心）的网站质量（边缘与中心）的贡献。 我们还将研究种群是否能够适应他们在气候变化下可能经历的环境因素的新组合，或者遗传相关性是否限制了新特征组合的进化。 这种类型的研究从根本上说是有趣的，但对社会也很重要。具有经济和文化重要性的物种正在经历气候变化的影响。通过了解什么在最近的过去限制了分布，什么在未来可能会限制分布，我们将能够更好地规划重要物种的保护和栽培。