Meeting Abstract
Organisms that encounter heterogeneous environments must perform under a wide range of conditions. For butterflies from temperate regions, distinct seasonal morphs adapt to specific thermal environments that vary from month to month. Seasonal adaptations often result in season-specific phenotypes, such as the induction of diapause in autumn morph butterflies. Diapause is a state of hibernation characterized by decreased metabolic activity and developmental arrest. Diapause allows butterflies to tolerate the harsh winter conditions that are normally unsuitable for ectotherms. In the context of climate change, shifts in seasonality and increased frequency of temperature anomalies may expose seasonal morphs to unpredictable thermal environments to which they are not adapted. To better understand how individuals may respond to these seasonal and thermal challenges, we examined the diapause induction and termination in seasonal morphs of a Vermont population of Pieris rapae, the cabbage white butterfly. We found that diapause induction and termination in P. rapae is dependent on multiple environmental factors, including photoperiod and temperature. Moreover, diapause induction and termination depend not only on the conditions under which eggs and larvae are cultured, but also the conditions that diapausing pupae experience. Survival of diapausing pupae was negatively correlated with incubation temperature, suggesting that high temperature anomalies that occur in the winter may pose significant costs to this species. In addition, we present evidence of transgenerational effects on diapause. Taken together, our results suggest that diapause is a plastic trait that has evolved to be responsive to environmental change, but that warm winter temperature anomalies may impose limits on this species in the future.
