Temperature variability alters the stability and thresholds for collapse of interacting species

Abstract

Temperature variability and extremes can have profound impacts on populations and ecological communities. Predicting impacts of thermal variability poses a challenge because it has both direct physiological effects and indirect effects through species interactions. In addition, differences in thermal performance between predators and prey and non-linear averaging of temperature-dependent performance can result in complex and counterintuitive population dynamics in response to climate change. Yet the combined consequences of these effects remain underexplored. Here, modeling temperature-dependent predator-prey dynamics, we study how changes in temperature variability affect population size, collapse, and stable coexistence of both predator and prey, relative to under constant environments or warming alone. We find that the effects of temperature variation on interacting species can lead to a diversity of outcomes, from predator collapse to stable coexistence, depending on interaction strengths and differences in species thermal performance. Temperature variability also alters predictions about population collapse - in some cases allowing predators to persist for longer than predicted when considering warming alone, and in others accelerating collapse. To inform management responses that are robust to future climates with increasing temperature variability and extremes, we need to incorporate the consequences of temperature variation in complex ecosystems.