Before the brink: sublethal impacts of climate change on stingless bee flight performance

Abstract

AimWe aimed to understand the sublethal impacts of climate change on native bee ecology. We evaluated how flight performance, a key trait for predator escape, dispersal, and pollination, is impacted by temperature. We aimed to understand how species geographic ranges shape species thermal performance curves (TPCs) and determine species vulnerability to further warming. LocationAustralia Time periodPresent Major taxa studiedStingless bees MethodsWe tested the flight speed and acceleration of two species of stingless bees, Austroplebeia australis and Tetragonula carbonaria at seven test temperatures. We examined how the climate experienced by species throughout their ranges shapes their TPCs. Inferences were made on how sublethal increases in temperature will likely impact key ecological activities associated with flight by estimating the proportion of species geographic ranges that experience temperatures that exceed their thermal optima. ResultsSpecies TPCs reflected the thermal environments they inhabit. A. australis, which experiences greater thermal variation and hotter temperatures throughout their range, had a broader TPC and higher thermal optima. However, A. australis also had faster flight performance than T. carbonaria, rejecting the jack-of-all-trades master-of-none hypothesis. Further increases in temperature will reduce flight performance of T. carbonaria at a faster rate (due to their narrower TPCs) than A. australis, however, a larger proportion of the A. australis range is currently exposed to temperatures above their thermal optima. Main conclusionsClimates will impact species ecology before they reach their lethal limits. Our study supports the idea that species fundamental niche breadths are linked to their geographic ranges, but that trade-offs are not associated with flight performance and ability to perform across a broad range of temperatures. When assessing vulnerability to climate change, it is important to consider how temperature impacts species traits, but also the climates that species experience throughout their unique geographic ranges.