Strong phenotypic plasticity limits potential for evolutionary responses to climate change

TLDR

Phenotypic plasticity enables organisms to express multiple phenotypes from a single genome, yet its capacity to promote evolutionary adaptation to climate change remains contested. This study investigates seasonal plasticity and adaptive potential in an Afrotropical butterfly that produces distinct phenotypes in dry and wet seasons. By conducting a full‑factorial analysis of 72 individuals, the authors map the transcriptional architecture of plasticity, uncovering pervasive gene‑expression differences between seasonal phenotypes. The butterfly exhibits negligible intra‑population genetic variation for plasticity, implying specialization to a reliable seasonal cue; as climate change diminishes cue accuracy, maladaptive phenotype‑environment mismatches and intensified selection on reaction norms are expected, but the paucity of genetic variation limits evolutionary responses and threatens population persistence, rendering seasonally plastic species especially vulnerable.

Abstract

Abstract Phenotypic plasticity, the expression of multiple phenotypes from one genome, is a widespread adaptation to short-term environmental fluctuations, but whether it facilitates evolutionary adaptation to climate change remains contentious. Here, we investigate seasonal plasticity and adaptive potential in an Afrotropical butterfly expressing distinct phenotypes in dry and wet seasons. We assess the transcriptional architecture of plasticity in a full-factorial analysis of heritable and environmental effects across 72 individuals, and reveal pervasive gene expression differences between the seasonal phenotypes. Strikingly, intra-population genetic variation for plasticity is largely absent, consistent with specialisation to a particular environmental cue reliably predicting seasonal transitions. Under climate change, deteriorating accuracy of predictive cues will likely aggravate maladaptive phenotype-environment mismatches and increase selective pressures on reaction norms. However, the observed paucity of genetic variation for plasticity limits evolutionary responses, potentially weakening prospects for population persistence. Thus, seasonally plastic species may be especially vulnerable to climate change.