Variation in two phases of post‐winter development of a butterfly

Abstract

The temporal aspects of life cycle characteristics, such as diapause development, are under strong selection in seasonal environments. Finetuning of the life cycle may be particularly important to match the phenology of potential mates and resources as well as for optimizing abiotic conditions at eclosion. Here, we experimentally study the spring phenology of the orange tip butterfly, Anthocharis cardamines, by analysing post-winter pupal development in three populations along a latitudinal cline in each of Sweden and the United Kingdom. These countries differ substantially in their seasonal temperature profile. By repeatedly recording pupal weights, we established that post-winter development has two separate phases, with a more rapid weight loss in the second phase than in the first, likely corresponding to a ramping up of the rate of development. Variation in the duration of the first phase contributed more strongly than the second phase to the differences in phenology between the localities and sexes. We found that insects from Sweden had a faster overall rate of development than those from the United Kingdom, which is consistent with countergradient variation, as Sweden is colder during the spring than the United Kingdom. Similar trends were not observed at the within-country scale, however. A cogradient pattern was found within Sweden, with populations from the north developing more slowly, and there was no clear latitudinal trend within the United Kingdom. In all localities, males developed faster than females. Our results point to the importance of variation in the progression of post-winter development for spring phenology.

Effect of winter cold duration on spring phenology of the orange tip butterfly, Anthocharis cardamines

“…2014; Stålhandske et al. 2014). The number of days from introduction to the warm temperature treatment until hatching was recorded, with the day taken out of the cold considered as day zero.…”

“…Second, based on the two‐phase post‐winter development previously reported (Stålhandske et al. 2014), a measurement was performed on seven other pupae in the first phase of post‐winter development (following 3 days at 17°C). Third, a measurement was performed on four further pupae in the second phase (following 9 days at 17°C).…”

“…2014). There is an inherent increase in development rate nearer to emergence as well as an increased sensitivity to temperature closer to hatching (Gray 2009).…”

“…The post‐winter development of A. cardamines has previously been shown to have two distinct phases of linear weight loss (Stålhandske et al. 2014). The second phase shows a near four‐fold increase in the rate of weight loss compared to the first phase (Stålhandske et al.…”

“…The second phase shows a near four‐fold increase in the rate of weight loss compared to the first phase (Stålhandske et al. 2014). This ramping up of development may benefit insects, such that conspecifics in a local area are more likely to emerge at the same time, thereby increasing the chance of finding a mate.…”