Temperature influences inter-individual variability in morphological and physiological traits of Baja California chorus frog tadpoles

Inter-individual variability is the range of phenotypes within a population and can shape adaptive responses to environmental change. However, how temperature influences this variability remains unclear despite its importance for predicting population resilience to warming. We tested how rearing temperature (15°C and 22°C) affects both trait means and variability in time to stage, size, oxygen consumption rate (V˙O2) and swim speed in Baja California chorus frog (Pseudacris hypochondriaca) tadpoles. Mean time to stage and morphological traits decreased at 22°C, while mass-specific V˙O2 and swim speed increased. Variance (s2, absolute variation) was lower at 22°C for time to stage and mass, higher for mass-specific V˙O2, and similar for length and swim speed. Coefficient of variation (CV, relative variation) was higher at 22°C for mass, tail length and depth, and mass-specific V̇O2, indicating trait-specific changes in canalization. Log-transformed Q10 response ratios for trait means (lnRRQ10), variance (lnVRQ10) and CV (lnCVRQ10) revealed strong thermal sensitivity for means but more limited and trait-specific responses in variability. Thus, temperature effects on variability are trait-specific and variability does not always change with, or in the same direction as, trait means. These phenotypic changes may have ecological consequences that influence physiological performance during subsequent life stages. This article is part of the theme issue 'Embracing variability in comparative physiology: why it matters and what to do with it'.