Ecology & Evolution of Species Range Limits

所有生物在地理分布上都是有限的，但如何以及为什么会出现范围限制仍然知之甚少。这阻碍了对物种在气候变化期间是否会改变范围或灭绝的现实预测，并削弱了对加拿大濒危物种的有效保护，其中大多数物种处于加拿大南部的北方界限。我的研究的目标是更好地了解生态和进化过程，在短期内施加范围限制，并防止长期范围扩张。我和我的学生将通过填补下面描述的4个知识缺口来实现这个目标，每个缺口都是范围限制拼图中缺失的一块。 (1)范围限制被认为发生在环境降低生存和繁殖的程度足以使种群不能自我替换的地方。虽然移植到其范围之外的物种往往受到影响，但其性能下降往往不足以限制其分布。在这种情况下，扩散可能是有限的，但这是如何发生的是未知的。一个可能但未经检验的假设是，当一个物种扩散到未被占用的栖息地斑块时，范围限制发生在它从被占用的斑块灭绝的速度上。(2)在其分布范围内，一个物种可能出现在各种栖息地，栖息地的范围可能会缩小到范围限制。这反过来可能会减少物种持久性所需的栖息地斑块之间的成功传播。然而，栖息地宽度是否在范围边缘的变化很少被研究和根本的机制还不清楚。(3)稳定的范围限制被认为发生在适应失败的地方。最近的实验未能揭示适应的必要限制，但没有人研究在自然条件下多代人的适应。 (4)边缘种群适应范围以外条件的能力将受到生殖方式的强烈影响。植物经常将繁殖模式转向范围限制，但这是否会抑制或促进地理传播尚不清楚。我们解决这些目标，使用大规模的地理调查，操作移植实验和基因组分析与植物物种被证明是优秀的实验系统。这项研究将有助于回答生物学前沿的基本问题，并有助于保护濒危物种，管理外来入侵者，更好地预测物种对气候变化的反应;威胁加拿大生物多样性的关键环境问题。我的实验室是一个包容性的环境，在那里各级不同的学员学习高度可转移的技术技能，适合他们的兴趣和长期的职业目标，在学术界，资源管理和行业。目前与资源管理机构的伙伴关系扩大了培训范围，促进了大学研究人员、政府科学家和决策者之间的信息和技能转让。

All organisms are limited in geographic distribution, but how & why range limits occur are still poorly understood. This prevents realistic forecasting of whether species will shift ranges or go extinct during climate change and weakens effective conservation of Canadian species at risk most of which are at their northern limits in southern Canada. The goal of my research is to better understand the ecological and evolutionary processes that impose range limits over the short-term and prevent range expansion over the long term. My students and I will address this goal by filling 4 knowledge gaps described below, each of which is a missing piece of the range-limit puzzle. (1) A range limit is thought to occur where the environment reduces survival and reproduction sufficiently that populations are not self-replacing. Although species transplanted beyond their range often suffer, their reduced performance is often insufficient to limit the distribution. In such cases, dispersal may be limiting but how this occurs is unknown. A likely but untested hypothesis is that the range limit occurs where a species' dispersal into unoccupied habitat patches fails to keep pace with its extinction from occupied patches. (2) Across its range, a species may occur in a variety of habitats and the range of habitats occupied may narrow towards range limits. This may, in turn, reduce successful dispersal between habitat patches required for species persistence. However, whether habitat breadth changes at range edges has rarely been studied and underlying mechanisms are not understood. (3) Stable range limits are thought to occur where adaptation fails. Recent experiments have failed to reveal the necessary constraints on adaptation, but none have examined adaptation over multiple generations under natural conditions. (4) The capacity of peripheral populations to adapt to conditions beyond the range will be strongly influenced by reproductive mode. Plants often shift reproductive modes towards range limits, but whether this inhibits or facilitates geographic spread is unknown. We address these objectives using large-scale geographic surveys, manipulative transplant experiments and genomic analyses with plants species proven to be excellent experimental systems. This research will help answer fundamental questions at the forefront of biology and contribute to the conservation of species-at-risk, the management of exotic invaders, and better forecasting of species' responses to climate change; key environmental problems threatening Canadian biodiversity. My lab is an inclusive environment where diverse trainees at all levels learn highly transferable technical skills suited to their interests and long-term career goals in academia, resource management and industry. Ongoing partnerships with resource-management agencies broaden training and facilitate the transfer of information and skills between university researchers, government scientists and policy-makers.