Reduced Intraspecific Variation in Lake Trout Food Webs Under Warmer Temperatures and Smaller Ecosystem Sizes: Implications for Resilience

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University of Guelph

Abstract

Food web theory has illustrated that mobile top predators, such as lake trout, can be potent stabilizers of food webs due to their ability to shift foraging behaviours in response to changing conditions. Consistent with this, research has demonstrated that mean lake trout food web attributes (i.e., trophic position and nearshore coupling) structurally change across environmental gradients; however, intraspecific variation in these attributes across gradients has not been fully explored. This is critical to understand as intraspecific variation can promote the resilience of ecosystems by offering a portfolio of responses that can buffer populations against environmental perturbations. Here, we used stable isotope-based food web metrics to investigate how intraspecific variation changes across these fundamental gradients in Canadian boreal shield lakes. Our results show that warmer temperatures and smaller ecosystem sizes reduce the expression of intraspecific variation with clear implications for ecosystem resilience.

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food web structure, global change, intraspecific variation, environmental gradients, resilience

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