Effects of environmental warming during early life history on libellulid odonates

Abstract

Climate warming affects ectotherms globally, yet we know little regarding the variability in species’ responses to warming, particularly in early life stages. Additionally, intraspecific variation in response to warming is understudied but may determine species’ resilience to warming. To assess how temperature affects egg development rate in co-occurring dragonfly species, we manipulated temperature (range: 22–31 °C) and measured time to hatching. Warming decreased egg development time across all species, indicating that while climate warming will advance hatching phenology, maintained synchrony in hatching order will likely not affect species interactions. Our second experiment examined early life-history responses to warming in the dot-tailed whiteface (Leucorrhinia intacta (Hagen, 1861)) dragonfly. We measured time to hatching, hatchling size, growth rate, and survival at four temperatures (23–30 °C), including a treatment with increased thermal variation. Warming resulted in smaller hatchlings with increased growth and mortality rates, whereas higher thermal variation did not have effects different from those of warming alone. We observed significant intraspecific variation in the responses to warming in both egg development time and hatchling size and this variation was correlated with date of oviposition. High levels of intraspecific variation may be important in buffering populations from the effects of climate warming.