Differences in phenology, daily timing of activity, and associations of temperature utilization with survival in three threatened butterflies

Abstract

We used observational data collected during a mark-recapture study that generated a total of 7503 captures of 6108 unique individuals representing three endangered butterfly species to quantify inter-and intraindividual variation in temperature utilization and examine how activity patterns vary according to season, time of day, and ambient temperature. The Marsh Fritillary, the Apollo, and the Large Blue differed in utilized temperatures and phenology. Their daily activity patterns responded differently to temperature, in part depending on whether they were active in the beginning, middle or end of the season, in part reflecting interindividual variation and intraindividual flexibility, and in part owing to differences in ecology, morphology, and colouration. Activity temperatures varied over the season, and the Apollo and the Large Blue were primarily active at the highest available ambient temperatures (on the warmest days and during the warmest part of the day). The Marsh Fritillary was active early in the season and decreased activity during the highest temperatures. The relationship between individual lifespan and the average temperature was qualitatively different in the three species pointing to species-specific selection. Lifespan increased with an increasing range of utilized temperatures in all species, possibly reflecting that intra-individual flexibility comes with a general survival benefit.

Comprehensive phylogeny of Pieridae butterflies reveals strong correlation between diversification and temperature

“… 56 In warm seasons, sunlight and ambient temperature are the main factors influencing butterfly activity, and if conditions are not ideal, butterflies will shift the timing and length of their activity. 57 The diversification of white and yellow butterflies is higher in these environments with stable circadian temperatures. The climatic stability hypothesis 13 predicts that the tropics are especially diverse in part because the climate does not fluctuate much throughout the day or year.…”

“…However, extremely warm temperatures can reduce activity in some species. 57 Recognizing these trends is crucial in light of the current, unprecedentedly rapid increase in global temperatures during the Anthropocene, particularly our evidence that speciation rates decrease with increasing temperature.…”

Diversification is correlated with temperature in white and sulfur butterflies

“…In general, diversity is greater in the tropics, and these areas are often characterized by high temperatures that are generally more constant throughout the year (47). In warm seasons, sunlight and ambient heat are the main factors influencing butterfly activity, and if conditions are not ideal, butterflies will shift the timing and length of their activity (48). The diversification of white and yellow butterflies is higher in these environments with stable circadian temperatures.…”

“…Franzén et al (48) found that the survival of the palearctic papilionid Parnassius apollo is negatively affected by increased median temperatures and that there is a tendency for stabilizing selection with temperature in the lycaenid Phengaris arion (48). In general, if temperatures are extreme, behavior and morphology/wing coloration will adapt to regulate body temperature (51)(52)(53)(54).…”

“…This is especially true for Arctic species. However, extremely warm temperatures can reduce activity in some species (48). Recognizing such trends is crucial considering global temperature changes due to climate change, particularly in light of our evidence of speciation rate decreasing with increasing temperature.…”