Clinal variation in investment into reproduction versus maintenance suggests a ‘pace-of-life’ syndrome in a widespread butterfly

Abstract

Extreme weather events such as heat waves are predicted to increase in the course of anthropogenic climate change. Widespread species are exposed to a variety of environmental conditions throughout their distribution range, often resulting in local adaptation. Consequently, populations from different regions may vary in their capacity to deal with challenging conditions such as thermal stress. In this study, we investigated clinal variation in body size, fecundity, and oxidative markers along a pan-European latitudinal gradient in the green-veined white butterfly Pieris napi, and additionally gene expression in German individuals. We exposed butterflies from replicated Italian, German, and Swedish populations to cold, control, or hot temperatures for 24 h. Under hot conditions, molecular chaperones were up-regulated, while oxidative damage remained unaffected and levels of the antioxidant glutathione (GSH) were reduced under cold and hot conditions. Thus, the short-term exposure to heat stress did not substantially affect oxidative balance. Moreover, we found decreased body size and fecundity in cooler compared with warmer regions. Interestingly, oxidative damage was lowest in Swedish animals exhibiting (1) high levels of GSH, (2) low early fecundity, and (3) low larval growth rates. These results suggest that Swedish butterflies have a slower life style and invest more strongly into maintenance, while those from warmer regions show the opposite pattern, which may reflect a 'pace-of-life' syndrome.

Population‐specific responses of an insect herbivore to variation in host‐plant quality

“…It may thus indicate that storage reserves are more strongly reduced in the rapidly developing Italian individuals compared with German individuals. However, we could not confirm the earlier results on differences in development time, growth rates, and body size among Italian and German populations (Günter, Beaulieu, Franke, et al, 2020 ; Günter, Beaulieu, Freiberg, et al, 2020 ). This is, at least in part, likely due to the pronounced variation among populations within countries (see Figure S2 : Appendix S1 for further illustration), in combination with the low statistical power of nested GLMs when the number of replicates is low.…”

“…With regard to the main effects of geographic origin, a significant difference was found only for fat content. The higher fat content found in German butterflies fits the previously observed differences in lifestyles (Günter, Beaulieu, Franke, et al, 2020 ; Günter, Beaulieu, Freiberg, et al, 2020 ). It may thus indicate that storage reserves are more strongly reduced in the rapidly developing Italian individuals compared with German individuals.…”

“…To address this issue, we here used the temperate zone butterfly Pieris napi , which has already served as model organism in various studies on genetic adaptation and phenotypic plasticity. This species seems to possess pronounced plastic and genetic capacities (Espeland et al, 2007 ; Günter et al, 2019 ; Günter, Beaulieu, Franke, et al, 2020 ; Günter, Beaulieu, Freiberg, et al, 2020 ; Posledovich et al, 2014 ). For instance, recent studies documented that Italian as compared with German populations seem to have a selective premium on rapid development, being nevertheless larger in size owing to higher larval growth rates (Günter et al, 2019 ; Günter, Beaulieu, Franke, et al, 2020 ; Günter, Beaulieu, Freiberg, et al, 2020 ).…”

“…This species seems to possess pronounced plastic and genetic capacities (Espeland et al, 2007 ; Günter et al, 2019 ; Günter, Beaulieu, Franke, et al, 2020 ; Günter, Beaulieu, Freiberg, et al, 2020 ; Posledovich et al, 2014 ). For instance, recent studies documented that Italian as compared with German populations seem to have a selective premium on rapid development, being nevertheless larger in size owing to higher larval growth rates (Günter et al, 2019 ; Günter, Beaulieu, Franke, et al, 2020 ; Günter, Beaulieu, Freiberg, et al, 2020 ). Furthermore, feeding on plants grown at cooler temperatures or under drought stress increased the performance of P .…”

“…Our earlier work has indicated a much faster lifestyle (i.e., a more rapid development) in Italian than in German individuals, arguably to fit in additional generations per year (Günter et al, 2019 ; Günter, Beaulieu, Freiberg, et al, 2020 ). This rapid pace of life also seems to increase oxidative damage (Günter, Beaulieu, Franke, et al, 2020 ). We, therefore, predict that the more time‐stressed Italian populations are more sensitive to poor food quality as compared to their German counterparts, reflecting a cost of rapid development.…”