Testing ecological and evolutionary hypotheses for geographic range limits

了解物种的地理分布是生态学的一个核心目标，在我们努力应对气候变化对生物多样性的影响时，这已经成为一个紧迫的科学需求。为此，我的研究重点是了解物种范围限制的生态和进化驱动因素。我过去的工作表明，范围限制往往与物种的适宜栖息地限制密切相关。然而，偏离这一模式，以及物种未能跟踪气候变化的许多案例，突出了进一步探索影响范围限制的生态因素的必要性。此外，解释范围限制最终需要确定自适应在范围边缘失败的原因。这些需要动机三个短期目标：1。解释物种占据其潜在范围的程度的变化。范围限制是否反映了适宜栖息地的限制或对扩散的限制，可能取决于景观特征和物种特征。我的实验室将使用空间数据来模拟合适的栖息地和10种两栖动物的潜在范围。使用这些模型，我们将测试是否陡峭的环境梯度，物种的扩散能力，和/或本地殖民和灭绝动态影响物种在不同的地方填补其潜在的范围的程度。 2.在范围限值下评价物种相互作用的影响。物种间的相互作用对范围限制的重要性是高度争论的。此外，当非生物条件紧张时，物种间的相互作用是否会产生更大或更小的影响，这一点存在着相互矛盾的观点。我的实验室将使用eDNA来量化物种相互作用频率的变化，这些相互作用对低海拔，无害，三种两栖动物的范围限制，并将通过实验测试这些相互作用对每个物种的影响是否在与高海拔限制和低海拔限制相关的非生物条件下有所不同。 3.在范围的边缘测试适应的遗传约束。遗传变异的随机丢失和遗传变异在散布后的地点之间的移动都可能影响范围限制的遗传多样性，从而影响周边种群的适应潜力。我的实验室将使用基因组数据来量化长趾蝾螈范围边缘的遗传变异和种群连接。然后，我们将测试是否在何种程度上人口表现出适应不良的基因组特征预测基于字段的测量个人的表现。 除了丰富我们对物种分布范围限制的理解外，这项研究还将为5名研究生和5名以上本科生提供高级技能培训。学生获得的技能和知识将使他们能够从事各种职业，并使他们能够为科学发现和应用做出有意义的贡献。

Understanding species' geographic distributions is a central goal in ecology and has emerged as a pressing scientific need as we strive to address the effects of climate change on biodiversity. Towards this end, my research focuses on understanding the ecological and evolutionary drivers of species' range limits. My past work has demonstrated that range limits often closely align with the limits of suitable habitat for species. Yet, departures from this pattern, as well as numerous cases whereby species have failed to track climate change, highlight the need to further probe the ecological factors influencing range limits. Furthermore, explaining range limits ultimately requires determining why adaptation fails at the edge of the range. These needs motive three short-term objectives: 1. Explain variation in the extent to which species occupy their potential range. Whether range limits reflect the limits of suitable habitat or constraints on dispersal may depend on features of the landscape and on species traits. My lab will use spatial data to model suitable habitat and the potential ranges of ten amphibian species. Using these models, we will test whether the steepness of environmental gradients, the dispersal capabilities of species, and/or local colonization and extinction dynamics influence the extent to which species fill their potential ranges in different places. 2. Evaluate the effects of species interactions at range limits. The importance of species interactions to range limits is highly debated. Furthermore, there are conflicting ideas as to whether species interactions are more or less impactful when abiotic conditions are stressful. My lab will use eDNA to quantify changes in the frequency of species interactions towards the low elevation, putatively benign, range limits of three amphibians and will experimentally test whether the effects of these interactions on each species varies across abiotic conditions associated with high versus low elevation limits. 3. Test genetic constraints on adaptation at the edge of the range. Both the random loss of genetic variation and the movement of genetic variants between sites following dispersal may influence genetic diversity at range limits and thus the adaptive potential of peripheral populations. My lab will use genomic data to quantify genetic variation and population connectivity at the edge of the range of the long-toed salamander. We will then test whether the extent to which populations demonstrate genomic signatures of maladaptation predicts field-based measurements of individual performance. Apart from enriching our understanding of species' range limits, this research will provide advanced skills training for 5 graduate and >5 undergraduate students. The skills and knowledge gained by students will equip them for a variety of careers and allow them to make meaningful contributions to scientific discovery and application.