Sexual differences in the morphology and movement of a butterfly: Good shape does not make good dispersers

Abstract

Movements are involved in several routine processes and may scale up to important ecological processes such as dispersal. However, movement is affected by a wealth of factors including fl ight capacity and behavioural traits. Both frequently differ in the sexes, which may well affect movement. We here aim to disentangle the relative importance of sexual differences in fl ight capacity versus behaviour on small-scale movements under controlled laboratory conditions in the temperate-zone butterfl y Lycaena tityrus. The morphology of males is typically associated with increased fl ight capacity in this species. Nevertheless, the fl ight performances of the sexes did not differ, but the mobility of the females was higher. Thus, fl ight capacity and patterns of movement may not be intimately associated. Rather, the costs and benefi ts of fl ight seem to differ substantially between the sexes, with females being more mobile, potentially as a risk spreading strategy, while males are territorial and thus more sedentary. Thus, predictions regarding movement based on morphology are diffi cult.

Enhanced dispersal capacity in edge population individuals of a rapidly expanding butterfly

“…However, the fact that these butterflies also fly longer when forced to fly in the shaker test additionally suggests that they have a higher flight capacity. Similarly, flight willingness and capacity were previously found to correlate positively in Lycaena tityrus butterflies monitored in controlled environments (Reim et al., 2019). However, while such behavioral differences between edge and core populations as measured in the lab might be used in predictive models estimating metapopulation dynamics (Ovaskainen & Hanski, 2004), how they actually translate into dispersal differences under natural conditions remains unknown (Stevens et al., 2010).…”

“…found to correlate positively in Lycaena tityrus butterflies monitored in controlled environments (Reim et al, 2019). However, while such behavioral differences between edge and core populations as measured in the lab might be used in predictive models estimating metapopulation dynamics , how they actually translate into dispersal differences under natural conditions remains unknown (Stevens et al, 2010).…”