Thermal niche helps to explain the ability of dung beetles to exploit disturbed habitats

Victoria C. Giménez Gómez,José R. Verdú,Gustavo A. Zurita

doi:10.1038/s41598-020-70284-8

Abstract

In terrestrial ecosystems, insects face a wide range of temperatures among habitats and time; consequently, the thermal niche is one of the main determinants of habitat selection and temporal patterns of activity. The replacement of native forests changes micro-climatic conditions and reduces the diversity of dung beetles; however, the physiological mechanisms behind these changes are not clear. We explore the role of the thermal niche in dung beetles to explain the ability of native species to exploit human-created habitats. Using infrared thermography, we measured variables associated with the thermal niche in 17 native species and used linear mixed-effects model and ANOVAs to compare disturbed habitats and the native forest. Endothermy and body mass explained the ability of dung beetles to exploit human-created open habitats. Small and diurnal species with very low endothermy were able to exploit deforested open habitats; evening/nocturnal/crepuscular species showed similar body mass and high endothermy in all habitats. Regarding thermoregulation mechanisms, none of the species (except one) showed defined or efficient mechanisms of physiological thermoregulation. In view of the accelerated process of forest replacement and climate change, a more profound understanding of the physiological requirements of species is essential to predict and mitigate future extinctions.

Highlights

In terrestrial ecosystems, insects face a wide range of temperatures among habitats and time; the thermal niche is one of the main determinants of habitat selection and temporal patterns of activity
In tropical and subtropical forests, recent studies have shown a marked reduction in the abundance and taxonomic and functional diversity of dung beetles in land uses with complete loss of canopy cover, such as pastures devoted to cattle raising[2,3,4]
This knowledge gap on dung beetle thermal biology led us to ask the following question: can the thermal niche of dung beetles explain the occupation of disturbed habitats, and taxonomic and functional changes reported in previous studies? We tested this central question in the southern Atlantic forest of South America, one of the most diverse and threatened ecosystems w orldwide[15,16,17]

Summary

Introduction

Insects face a wide range of temperatures among habitats and time; the thermal niche is one of the main determinants of habitat selection and temporal patterns of activity. Individuals can regulate their temperature through behavior (e.g. posterior leg posture that affects turbulence convective cooling during the flight)[31], morphology (e.g. color, size) and/or physiology (e.g. hemolymph circulation, respiration)[1,28] Both the endothermy and thermoregulation of insects have received much attention due to their central role in their ecology (competition for a resource and/or establishment of reproductive pairs), e volution[28,32], distribution, and response to climatic c hanges[28,33,34]. Since in this study we independently evaluated and discussed both processes, we considered them separately

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