Supplementary material from "Spatio-temporal environmental variation mediates geographical differences in phenotypic responses to ocean acidification"

Phenotypic plasticity is expected to play a major adaptive role in the response of species to ocean acidification (OA), by providing broader tolerances to changes in pCO₂ conditions. However, tolerances and sensitivities to future OA may differ among populations within a species because their particular environmental context and genetic backgrounds. Here, using the climatic variability hypothesis (CVH), we explored this conceptual framework in populations of the sea urchin Loxechinus albus across natural fluctuating pCO₂/pH environments. Although elevated pCO₂ affected the morphology, physiology, development and survival of sea urchin larvae, the magnitude of these effects differed among populations. These differences were consistent with the predictions of the CVH showing greater tolerance to OA in populations experiencing greater local variation in seawater pCO₂/pH. Considering geographical differences in plasticity, tolerances and sensitivities to increased pCO₂ will provide more accurate predictions for species responses to future OA.