Rossi Aviva J, Klinger Robert C, Hellwig Elise C, Van Vuren Dirk H
Department of Wildlife, Fish, & Conservation Biology University of California, Davis One Shields Avenue Davis California 95616 USA.
Western Ecological Research Center U.S. Geological Survey 2761 Glenbrook Way Bishop California 93514 USA.
Ecol Evol. 2023 Mar 31;13(4):e9949. doi: 10.1002/ece3.9949. eCollection 2023 Apr.
Species with different ecological niches will likely exhibit distinct responses to a changing environment. Differences in the magnitude of niche specialization may also indicate which species may be more vulnerable to environmental change, as many life-history characteristics are known to affect climate change vulnerability. We characterized the niche space of three sympatric high-elevation ground-dwelling squirrels, yellow-bellied marmot (), Belding's ground squirrel (), and golden-mantled ground squirrel (), in the alpine and upper subalpine regions of the Sierra Nevada in California. We used 5879 observations of individual squirrels, collected from 4 years (2009-2012) of transect survey data, to quantify which ecogeographical variable types (climate, topography, or landcover) were most important in defining the niche of each species. We conducted Ecological Niche Factor Analysis to quantify the niche and generate indices of "marginality" (magnitude of selection) and "specialization" (narrowness of niche space). All three species demonstrated differential use of niche space when compared to the available niche space. Moreover, the relative importance of the variables shaping the niche differed among these species. For example, the presence of meadows was important in defining the niche for and , but the presence of conifers was important to . Precipitation was important in defining the niche for all three species, positively so for , and negatively for the other two species. The niche breadth of these three species was also positively associated with geographic range size. Mammals in high-elevation mountain systems often are perceived as vulnerable to climate shifts, but our results underscore the importance of also including non-climate-based factors in defining the niche. The overall magnitude of niche selection for all three species was driven by a combination of topographic, climatic, and landcover factors; thus, efforts to forecast areas where these species can persist in the future need to evaluate from more than just a climatic perspective.
具有不同生态位的物种可能会对不断变化的环境表现出不同的反应。生态位专业化程度的差异也可能表明哪些物种可能更容易受到环境变化的影响，因为许多生活史特征已知会影响对气候变化的脆弱性。我们描述了加利福尼亚内华达山脉高山和亚高山上部地区三种同域分布的高海拔地栖松鼠的生态位空间，即黄腹旱獭（ ）、贝尔丁地松鼠（ ）和金背地松鼠（ ）。我们使用从4年（2009 - 2012年）样带调查数据中收集的5879个个体松鼠观测数据，来量化哪些生态地理变量类型（气候、地形或土地覆盖）在界定每个物种的生态位时最为重要。我们进行了生态位因子分析，以量化生态位并生成“边缘性”（选择强度）和“专业化”（生态位空间的狭窄程度）指数。与可用生态位空间相比，所有这三个物种都表现出对生态位空间的不同利用。此外，塑造生态位的变量的相对重要性在这些物种之间也有所不同。例如，草地的存在对 和 的生态位界定很重要，但针叶树的存在对 很重要。降水对所有这三个物种的生态位界定都很重要，对 呈正相关，对其他两个物种呈负相关。这三个物种的生态位宽度也与地理分布范围大小呈正相关。高海拔山地系统中的哺乳动物通常被认为容易受到气候变化的影响，但我们的结果强调了在界定生态位时纳入非气候因素的重要性。所有这三个物种的生态位选择的总体强度是由地形、气候和土地覆盖因素共同驱动的；因此，预测这些物种未来能够持续生存的区域的努力需要从不仅仅是气候的角度进行评估。
