Testing how species interactions and evolution accelerate or decelerate climate-driven range shifts

在全球范围内，许多物种的活动范围正在向极地和海拔向上移动。然而，大多数观察到的距离变化小于我们预测的物种是否完美地跟踪气候，而且它们有很大的不同，一些沿着特殊的方向移动，另一些则完全不移动。我的长期目标是解释哪些物种落后于气候变化，以及为什么要更好地预测和管理对生物多样性的影响。我的短期目标是研究气候驱动的范围变化是如何通过(1)物种相互作用、(2)进化动力学和(3)两者之间的反馈来加速或减速的。(1)如果物种与其他物种的相互作用如何影响扩散速率(在射程变化的扩大边缘)和下降速度(在收缩边缘)，就会出现气候跟踪的变化。例如，一些物种可能无法在气候适宜但有更好竞争对手的地区定居。这项拟议的工作将沿着横跨喀斯喀特山脉30种植物海拔范围的气候梯度，实验性地操纵关键物种的相互作用、种子捕食和竞争，以确定某些功能组或范围边缘是否更受物种相互作用的影响。(2)在理论上，进化可以对射程变化产生不同的影响，例如，当更好的分散者在扩张射程边缘集中并交配时，加速射程扩张；当有害突变在扩张射程边缘的小种群中偶然增加时，射程扩张减速；或者如果种群能够迅速适应不断恶化的条件，则射程收缩速度减慢。这项拟议的工作将测试猴花物种内部和之间范围扩展速度的差异是否与有害突变积累的差异有关。它还将衡量特征进化的人口统计学影响，以确定对极端气候扰动的快速适应是否可以拯救种群并防止范围缩小。(3)物种间的相互作用可能会以不可预测的方式改变对气候变化的进化反应，而不检查它们的反馈。例如，竞争可能会通过导致额外的选择来加速对不断变化的环境的适应，尽管种群规模会减少，或者通过减缓范围扩张的速度来减缓不断扩大的边缘的有害突变的积累，从而允许更大的种群规模和遗传多样性的建立。我们将使用浮萍的新型实验室微观世界来研究物种相互作用如何影响沿着移动的温度梯度的射程演化。这项研究将涉及国际合作、高级技能发展和网络，面向1名博士后、5名研究生和10名本科生。受训者将具备在私营部门、政府或学术界从事职业的可转让技能，以及帮助应对加拿大气候变化的生态影响的知识。

Globally many species' ranges are shifting poleward and up in elevation. However, most observed range shifts are less than we would predict if species were perfectly tracking climate, and they differ substantially, with some moving in idiosyncratic directions and others not moving at all. My long-term objective is to explain which species lag behind climate change and why to better predict and manage impacts on biodiversity. My short-term objectives are to investigate how climate-driven range shifts are accelerated or decelerated by (1) species interactions, (2) evolutionary dynamics and (3) feedbacks between the two. (1) Variation in climate tracking will arise if species differ in how interactions with other species affect rates of spread (at expanding edges of range shifts) and decline (at contracting edges). For example, some species might be unable to colonize areas that have become climatically suitable but contain better competitors. The proposed work will experimentally manipulate key species interactions, seed predation and competition, along climate gradients spanning 30 plants' elevation ranges in the Cascade Mountains, to determine whether certain functional groups or range edges are more influenced by species interactions. (2) In theory evolution can have diverse effects on range shifts, such as accelerating range expansion as better dispersers concentrate and mate at expanding range edges, decelerating range expansion as harmful mutations increase by chance in small populations at expanding range edges, or decelerating rates of range contraction if populations are able to rapidly adapt to deteriorating conditions. The proposed work will test whether variation in rates of range expansion within and among monkeyflower species is related to differences in accumulation of deleterious mutations. It will also measure the demographic effects of trait evolution to determine whether rapid adaptation to extreme climatic perturbation can rescue populations and prevent range contraction. (3) Species interactions could modify evolutionary responses to climate change in ways that are unpredictable without examining their feedbacks. For example, competition could accelerate rapid adaptation to a changing environment by causing additional selection, despite reducing population size, or alleviate the build-up of deleterious mutations at expanding edges by slowing rates of range expansion, allowing larger population sizes and genetic diversity to build up. We will use novel lab microcosms with duckweeds to study how species interactions affect range evolution along a moving temperature gradient. The research will involve international collaboration, advanced skill development, and networking for 1 postdoctoral, 5 graduate, and 10 undergraduate trainees. Trainees will be equipped with transferable skills for careers in private sector, government, or academia, and knowledge to help address the ecological impacts of climate change in Canada.