Competition and resource depletion shape the thermal response of population fitness in Aedes aegypti

Paul J Huxley,Samraat Pawar,Lauren J Cator,Kris A Murray

doi:10.1038/s42003-022-03030-7

Paul J Huxley, Samraat Pawar + Show 2 more

Open Access

https://doi.org/10.1038/s42003-022-03030-7

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Abstract

Mathematical models that incorporate the temperature dependence of lab-measured life history traits are increasingly being used to predict how climatic warming will affect ectotherms, including disease vectors and other arthropods. These temperature-trait relationships are typically measured under laboratory conditions that ignore how conspecific competition in depleting resource environments—a commonly occurring scenario in nature—regulates natural populations. Here, we used laboratory experiments on the mosquito Aedes aegypti, combined with a stage-structured population model, to investigate this issue. We find that intensified larval competition in ecologically-realistic depleting resource environments can significantly diminish the vector’s maximal population-level fitness across the entire temperature range, cause a ~6 °C decrease in the optimal temperature for fitness, and contract its thermal niche width by ~10 °C. Our results provide evidence for the importance of considering intra-specific competition under depleting resources when predicting how arthropod populations will respond to climatic warming.

Highlights

Mathematical models that incorporate the temperature dependence of lab-measured life history traits are increasingly being used to predict how climatic warming will affect ectotherms, including disease vectors and other arthropods
Such predictions typically arise from mathematical models that incorporate thermal performance curves (TPCs) for vector life history traits, such as juvenile development and mortality, which together define the TPC of maximal population growth rate[5]
Ae. aegypti is expected to be strongly regulated by conspecific competition between larvae[13,14], because this stage of the species’ lifecycle is confined to small isolated water bodies that are susceptible to infrequent resource inputs and, resource depletion[15,16,17,18]

Summary

Introduction

Mathematical models that incorporate the temperature dependence of lab-measured life history traits are increasingly being used to predict how climatic warming will affect ectotherms, including disease vectors and other arthropods. These temperature-trait relationships are typically measured under laboratory conditions that ignore how conspecific competition in depleting resource environments—a commonly occurring scenario in nature—regulates natural populations. Other studies have predicted that warming will increase the global invasion potential of Aedes aegypti, a principal vector of dengue, yellow fever and chikungunya[4] Such predictions typically arise from mathematical models that incorporate thermal performance curves (TPCs) for vector life history traits, such as juvenile development and mortality, which together define the TPC of maximal population growth rate (rm, a measure of population fitness)[5]. Our findings allow us to infer that there are thresholds of resource availability, below which intensifying competition causes a dramatic change in this temperature dependence of fitness

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