Is spider resting metabolic rate more strongly associated with ecological guild or extreme habitat conditions?

Abstract

Ectotherms with lower maintenance costs and broader environmental tolerancesare generally more resilient in human-altered landscapes and under currentclimate change, enhancing their chances of survival and colonization. In thisstudy, we explored how habitat use and foraging strategy are associated with theresting metabolic rate (RMR) of spiders from habitats with significant temperaturevariability due to anthropogenic disturbance: native forests and young pine plantations,both in the Southern Atlantic Forest. Using open-flow respirometry at25C, we measured CO2 production in immobile spiders to calculate their RMR.Key findings include: (1) all spiders showed 22%–57% lower RMR than predictedby standard metabolic equations; (2) continuous gas exchange patterns, typical ofmesic-adapted species, were observed in all cases; (3) the metabolic rate scalingexponent was 0.65; (4) there were no significant RMR differences between habitats,but a negative correlation between RMR and microhabitat thermal amplitudewas noted; and (5) active foragers had higher RMRs than passive foragers. Thesefindings enhance our understanding of spider biology, physiology, and ecology,particularly in their responses to anthropogenic stressors.