Journal Article

Disentangling the relative influences of global drivers of change in biodiversity

Gallant, Daniel, Berteaux, Dominique, Lecomte, Nicolas

2020

Overview

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. This research is a critical investigation of a widely accepted climate change hypothesis explaining species range expansions. Its results show the importance of considering a wider scope of global drivers to explain observed biological change.

• Publisher: Wiley,Blackwell Publishing Ltd
• Subject: Animal behavior / animal ecology / anthropocene / Anthropogenic factors / Archives & records / Arctic region / Biodiversity / biogeography / Climate change / cooling / distribution / Ecological effects / ecosystems / Food / Food sources / food subsidies / Foxes / fur / fur trade / Habitat changes / habitats / Historical ecology / human activity / Human influences / humans / Hypotheses / RESEARCH ARTICLE / Statistical models / Subsidies / Summer / Thermal stress / Tundra / Vulpes lagopus / Vulpes vulpes / Winter