Colorado State University, Fort Collins, CO, USA.
Southwest Fisheries Science Center, National Marine Fisheries Service, Santa Cruz, CA, USA.
Glob Chang Biol. 2021 Aug;27(15):3519-3531. doi: 10.1111/gcb.15639. Epub 2021 May 15.
Global loss of biodiversity has placed new urgency on the need to understand factors regulating species response to rapid environmental change. While specialists are often less resilient to rapid environmental change than generalists, species-level analyses may obscure the extent of specialization when locally adapted populations vary in climate tolerances. Until recently, quantification of the degree of climate specialization in migratory birds below the species level was hindered by a lack of genomic and tracking information, but recent technological advances have helped to overcome these barriers. Here we take a genome-wide genetic approach to mapping population-specific migratory routes and quantifying niche breadth within genetically distinct populations of a migratory bird, the willow flycatcher (Empidonax traillii), which exhibits variation in the severity of population declines across its breeding range. While our sample size is restricted to the number of genetically distinct populations within the species, our results support the idea that locally adapted populations of the willow flycatcher with narrow climatic niches across seasons are already federally listed as endangered or in steep decline, while populations with broader climatic niches have remained stable in recent decades. Overall, this work highlights the value of quantifying niche breadth within genetically distinct groups across time and space when attempting to understand the factors that facilitate or constrain the response of locally adapted populations to rapid environmental change.
全球生物多样性的丧失使得人们更加迫切地需要了解调节物种对快速环境变化反应的因素。尽管专家通常比通才更不容易适应快速的环境变化，但当局部适应的种群在气候容忍度上存在差异时，物种水平的分析可能会掩盖专业化的程度。直到最近，由于缺乏基因组和跟踪信息，量化候鸟在种以下水平的气候专门化程度一直受到阻碍，但最近的技术进步有助于克服这些障碍。在这里，我们采用全基因组遗传方法来绘制特定种群的迁徙路线，并量化迁徙鸟类柳树鹀（Empidonax traillii）中遗传上不同种群的生态位宽度，该鸟类在其繁殖范围内的种群数量下降程度存在差异。虽然我们的样本量仅限于该物种内遗传上不同的种群数量，但我们的结果支持了这样一种观点，即在季节间气候生态位狭窄的柳树鹀的局部适应种群已经被联邦列为濒危或急剧下降，而具有较宽气候生态位的种群在最近几十年保持稳定。总的来说，这项工作强调了在尝试理解促进或限制局部适应种群对快速环境变化的反应的因素时，在时间和空间上量化遗传上不同群体的生态位宽度的价值。
