Thermal niche dimensionality could limit species’ responses to temperature changes: Insights from dung beetles

Abstract

[Aim]: Adequate responses of species to climate changes require that thermal changes remain compatible across different key biological aspects (e.g. reproduction, feeding and development). However, limits of thermal compatibility to such biological aspects are largely unknown in extant ectotherm groups. To fill this gap, we studied the in-traspecific congruence of thermal responses across biological aspects.

[Location]: Iberian Peninsula.

[Taxon]: Scarabaeidae Dung beetles.

[Methods]: We studied the role of temperature in determining the diel, seasonal and geographical occurrences of 16 dung beetle species. We fitted polynomial GLMs of the abundance/occurrence of each species as a function of temperature and alterna-tive predictors for each spatiotemporal scale, using deviance partitioning to explore the relative contribution of temperature. We used the fitted models to estimate real-ized thermal niche attributes at these three spatiotemporal scales, and assessed their intraspecific congruence through the correlation of niche attributes from different scales.

[Results]: We found that temperature has relatively low—but not negligible—explanatory capacity at the three spatiotemporal scales, once alternative predictors are taken into account. More importantly, the estimated thermal responses were largely incongru-ent across scales, indicating that these species have multidimensional thermal niches.

[Main conclusions]: The multidimensionality of thermal niches entails that species’ adjustments to fulfil temperature requirements for one biological aspect (such as sea-sonal ontogenetic cycles) may result in detrimental effects on other elements (e.g. diel activity). These trade-offs could expose individuals to inadequate temperatures at certain moments, reducing populations’ performance. Paradoxically, the weak effects of temperature we found may have severe consequences for species responses to warming if temperature regulates essential aspects of their biology in divergent ways.