CAREER: Individual-based species distribution models for understanding the demographic drivers of range shifts and their consequences for biodiversity

为了应对气候条件的变化，许多物种的地理分布，即物种范围，正在向较高纬度(向两极)转移，因为它们正在从较低纬度消失。虽然许多研究都集中在了解物种范围在不断扩大的前沿，在那里物种正在变得更加丰富，但对理解为什么在较低纬度的边缘种群会减少的关注较少。这个项目关注于在阿巴拉契亚山脉南部发现的鸟类物种，并研究了各种因素如何导致它们在这个范围边缘的数量下降。具体地说，这项研究将测试以下因素的相对重要性：物种对极端温度和干旱的耐受性、与其他物种的竞争、食物来源的可获得性与筑巢时间之间的不匹配，以及与种群规模较小和行动模式有限相关的因素。鉴于环境条件的变化和物种分布的预期变化，这项研究的结果将对保护和管理物种的努力具有重要意义。该项目还将培训研究生和本科生开发不同的生态建模方法，将开发一个公民科学计划，并将使缺乏服务的高中STEM学生接触田间生态学。理论工作预测，不断变化的环境条件可能会与生态过程相互作用，导致范围转移。然而，经验研究未能确定物种耐受性和竞争、物候错配、密度依赖和扩散限制等机制在解释这些分布转移方面的相对贡献。这项研究使用实验和观测数据来确定生理耐受性和其他机制在解释阿巴拉契亚山脉南部低纬度范围内发现的几种鸟类的种群动态中所起的相对作用。这项研究将通过开发新的时空点过程模型来克服物种分布模型在理解射程变化方面的局限性，该模型可以适用于经验数据。这一框架的独特之处在于，它能够在多个空间和时间尺度上描述和预测生态过程，同时考虑到人口比率的个体差异。这项研究将促进对范围变化的科学理解，将产生一个整合理论和应用生态学的新框架，并将开发预测模型，为生物多样性的保护提供信息。

In response to changing climatic conditions, the geographic distribution of many species, i.e., species ranges, are shifting to higher latitudes (towards the poles) as they are disappearing from lower latitudes. While much research has focused on understanding species ranges at their expanding, leading-edges where they are becoming more abundant, less emphasis has been placed on understanding why populations would be declining at their lower latitude, trailing-edges. This project focuses on bird species found at their trailing-edges in the southern Appalachian Mountains, and examines how a variety of factors may contribute to their decline in numbers at this edge of their range. Specifically, this research will test the relative importance of: species tolerance to extreme temperatures and drought, competition with other species, mismatches between the availability of food sources and nesting times, and factors associated with having small population sizes and limited movement patterns. The results of this study will be important in efforts to conserve and manage species given changing environmental conditions and expected changes in the distributions of species. This project will also train graduate and undergraduate students in the development of different ecological modeling approaches, will develop a citizen sciences program, and will expose underserved high school STEM students to field ecology. Theoretical work predicts that changing environmental conditions can interact with ecological processes to cause range shifts. Empirical studies have, however, failed to identify the relative contributions of species tolerances and mechanisms such as competition, phenological mismatches, density-dependence, and dispersal limitations in explaining these distributional shifts. This study uses experimental and observational data to determine the relative role physiological tolerances and other mechanisms play in explaining the population dynamics of several bird species found at their low-latitude range limits in the southern Appalachian Mountains. This study will overcome the limitations of species distribution models for understanding range shifts by developing novel spatio-temporal point process models that can be fitted to empirical data. This framework is unique in its ability to describe and predict ecological processes at multiple spatial and temporal scales while accounting for individual variation in demographic rates. This research will advance scientific understanding of range shifts, will produce a new framework for integrating theoretical and applied ecology, and will develop predictive models to inform the conservation of biodiversity.