Effects of temperature and drought on early life stages in three species of butterflies: Mortality of early life stages as a key determinant of vulnerability to climate change?

Anthropogenic climate change poses substantial challenges to biodiversity conservation. Well‐documented responses include phenological and range shifts, and declines in cold but increases in warm‐adapted species. Thus, some species will suffer while others will benefit from ongoing change, although the biological features determining the prospects of a given species under climate change are largely unknown. By comparing three related butterfly species of different vulnerability to climate change, we show that stress tolerance during early development may be of key importance. The arguably most vulnerable species showed the strongest decline in egg hatching success under heat and desiccation stress, and similar pattern also for hatchling mortality. Research, especially on insects, is often focussed on the adult stage only. Thus, collating more data on stress tolerance in different life stages will be of crucial importance for enhancing our abilities to predict the fate of particular species and populations under ongoing climate change.