Multiple temperature effects on phenology and body size in wild butterflies predict a complex response to climate change

Abstract

Citation: Davies, W. J. 2019. Multiple temperature effects on phenology and body size in wild butterflies predict a complex response to climate change. Ecology 100(4):Abstract. Temperature-induced alterations in phenology and body size are the cumulative outcome of sequential effects impacting development and are universal responses to climate change. Most studies have so far focused on phenological responses to warming in multiple taxa across space and time, or the ontogenetic effects of temperature in the laboratory. I here complement this work by investigating shifts in phenology and body size (wing length) attributable to temperature changes operating over the entire lifespan of the univoltine orange-tip butterfly Anthocharis cardamines in a single wild population over 14 generations. Phenology was affected by temperatures during three discrete periods in the year prior to emergence, corresponding to late larval/early pupal life, the onset of the chilling period required to break pupal diapause, and postdiapause pupal development prior to eclosion. Higher temperatures during late larval/early pupal life and postdiapause pupal development advanced the subsequent emergence of the butterflies, whereas higher temperatures at the onset of the chilling period retarded it. The synchronization of the butterflies' emergence schedule increased when pupae were exposed to milder midwinter temperatures. Wing length increased with warmer temperatures at distinct points in the early and midpupal periods; such direct effects of temperature on body size could complement season length effects in explaining the reversal of the temperature-size rule in univoltine insects. The periods during which temperature affected the phenology of the butterfly only partially overlapped those affecting the first flowering date of its host plants lady's smock (Cardamine pratensis) and garlic mustard (Alliaria petiolata). Observed thermal effects on flowering time, emergence timing, and emergence synchronization indicate that phenological convergence as well as phenological mismatching could affect hostplant availability and diet breadth; thermal effects on body size imply that important population-level processes could be impacted through correlated changes in fecundity and dispersal rate. In general, the combined effects of phenological and ontogenetic responses to temperature changes across the whole lifespan will likely be important in modeling the demographic responses of interacting species to climate change.

The influence of ecological and life history factors on ectothermic temperature–size responses: Analysis of three Lycaenidae butterflies (Lepidoptera)

“…This may also be the reason for the decrease in adult size when higher temperatures occur during the pupal stage, because the pupa of this species also produces secretions and sounds to attract ants (Thomas & Lewington, 2014). This contrasts with results in a study of the univoltine butterfly Anthocharis cardamines, which is not associated with ants in the larval or pupal stages, which found that an increase in adult body size was correlated with temperature increases during the pupal stage of development, and that both sexes responded in the same way (Davies, 2019).…”

“…Polyommatus bellargus , for example, overwinters as a larvae whereas P. argus and P. coridon overwinter as eggs (Thomas & Lewington, ). Yet, they are all direct developers (i.e., there is no pupal diapause) and therefore may be subject to more seasonal time constraints and variation than species which diapause in the pupal phase, such as A. cardamines (Davies, ). This may explain why all three lycaenid species we have studied, and H. comma , respond to temperature in the larval stage (Table ; Fenberg et al, ) but the pierid butterfly A. cardamines , which overwinters in the pupal stage, instead responds to temperature in the pupal stage (Davies, ).…”

Intra‐ and interspecific variation in the responses of insect phenology to climate

“…has shown the effects of temperature during three time-windows on emergence dates (Davies, 2019). However, our results are consistent with evidence for larger effects of temperature on later immature stages in Lepidoptera (e.g.…”

“…Roy et al., 2015). We cannot rule out the possibility of temperature effects on phenology at other times of the year because our statistical technique was limited to one time‐window per model, and recent research on a population of one of the focal species ( A. cardamines ) has shown the effects of temperature during three time‐windows on emergence dates (Davies, 2019). However, our results are consistent with evidence for larger effects of temperature on later immature stages in Lepidoptera (e.g.…”

Changes in phenology and abundance of suction‐trapped Diptera from a farmland site in the UK over four decades

“…Therefore, studying changes in their phenology and abundance is a prerequisite to understanding ecosystem responses to environmental changes. Changes in phenology and abundance in response to environmental changes vary with species and spatial scale (Bell et al, 2018;Frik et al, 2020), and generalisation has proved elusive (Diez et al, 2012;Davies, 2019).…”