Chaire de recherche du Canada en biodiversité nordique and Centre d'Études Nordiques, Université du Québec à Rimouski, Rimouski, QC, Canada.
Chaire de recherche du Canada en écologie polaire et boréale and Centre d'Études Nordiques, Université de Moncton, Moncton, NB, Canada.
J Anim Ecol. 2020 Feb;89(2):565-576. doi: 10.1111/1365-2656.13090. Epub 2019 Sep 9.
The poleward range shift of the red fox (Vulpes vulpes) > 1,700 km into the Arctic is one of the most remarkable distribution changes of the early twentieth century. While this expansion threatens a smaller arctic ecological equivalent, the arctic fox (Vulpes lagopus), the case became a textbook example of climate-driven range shifts. We tested this classical climate change hypothesis linked to an important range shift which has attracted little research thus far. We analysed Canadian fur harvest data from the Hudson's Bay Company Archives (14 trading posts; 1926-1950), testing hypotheses based on changes in summer and winter climates. Summer warming might have triggered a bottom-up increase in ecosystem productivity, while winter warming might have lowered thermal stress, both favouring red fox expansion. Additionally, we evaluated the hypothesis that red fox expansion was driven by the appearance of human sedentary sites (n = 110) likely bringing food subsidies into the unproductive tundra. Analysis of red fox expansion chronologies showed that expansion speed was higher during warmer winters. However, the expansions occurred under both cooling and warming trends, being faster during cooler summers in the Baffin Island region. The increasing proportion of red fox in fox fur harvests was best explained by human activity, while generalized linear mixed models also revealed a marginal effect of warmer winters. Generalized additive models confirmed human presence as the most important factor explaining rates of change in the proportion of red fox in fox fur harvests. Using historical ecology, we disentangled the relative influences of climate change and anthropogenic habitat change, two global drivers that transformed arctic biodiversity during the last century and will likely continue to do so during this century. Anthropogenic food subsidies, which constitute stable food sources, facilitated the invasion of the tundra biome by a new mammalian predator and competitor, with long-term consequences that still remain to be understood.
北极狐（Vulpes vulpes）的活动范围向极地方向迁移了>1700 公里，这是 20 世纪初最显著的分布变化之一。虽然这种扩张对较小的北极生态系统构成了威胁，但北极狐（Vulpes lagopus）的情况成为了气候驱动范围变化的典型案例。我们检验了这一与重要的范围变化相关的经典气候变化假说，而这一变化到目前为止还很少受到研究关注。我们分析了哈德逊湾公司档案馆（14 个贸易站；1926-1950 年）的加拿大皮毛采集数据，根据夏季和冬季气候的变化来检验假说。夏季变暖可能引发了生态系统生产力的自下而上的增加，而冬季变暖可能降低了热应激，这两种情况都有利于北极狐的扩张。此外，我们还评估了这样一种假设，即北极狐的扩张是由人类定居点的出现（n=110）驱动的，这些定居点可能会将食物补贴带入没有生产力的苔原。对北极狐扩张时间表的分析表明，在较暖的冬季，扩张速度更高。然而，扩张发生在冷却和变暖趋势下，在巴芬岛地区较凉爽的夏季扩张速度更快。狐皮采集量中北极狐比例的增加与人类活动的关系最为密切，广义线性混合模型也揭示了温暖冬季的边际效应。广义加性模型证实，人类的存在是解释狐皮采集量中北极狐比例变化率的最重要因素。通过历史生态学，我们厘清了气候变化和人为栖息地变化这两个全球驱动因素的相对影响，这两个因素在上个世纪改变了北极地区的生物多样性，并可能在本世纪继续产生影响。人为的食物补贴构成了稳定的食物来源，促进了一种新的哺乳动物捕食者和竞争者对苔原生物群落的入侵，其长期后果仍有待理解。
