Emigration propensity and flight performance are decoupled in a butterfly

Abstract

Dispersal, defined as any movements potentially leading to gene flow, is a major process driving a species’ capacity to cope with human‐induced environmental modifications. However, the dispersal process is multi‐causal, which currently hinders predictions regarding a species’ resilience to global change. We used a multifaceted approach to disentangle the relative importance of a suite of dispersal‐related factors in the butterfly Lycaena tityrus, including condition‐ (morphology and behavior) and context‐ (environmental) dependent factors. Experiments were conducted at an experimental platform dedicated to study dispersal, the Metatron, to record emigration propensity in two‐patch experimental metapopulations under different environmental conditions. The butterflies’ individual condition was subsequently assessed in the laboratory. Individual condition did not generally influence emigration propensity. We detected a significant sex bias in emigration propensity, being generally higher in females than in males, but in a context‐dependent manner. The environmental context affected emigration propensity, which was higher when habitat quality was poor. Our results show that emigration is not random in L. tityrus, but is rather an active process triggered by sex and habitat quality. Our main finding was that individual condition, and particularly flight ability measured by a performance test, was not related to emigration propensity in experimental metapopulations. Our results may have important implications for forecasting future species distributions, as deteriorating environmental contexts are likely to increase emigration whatever the individual condition is.

Sexual differences rather than flight performance underlie movement and exploration in a tropical butterfly

“…This could indicate that flight performance, on the one hand, and movement and exploration on the other are not intimately associated in B. anynana, which has been suggested before . Interestingly, this is also in line with experiments under semi-natural conditions in the butterfly Lycaena tityrus, where emigration propensity was not linked to individual condition and flight ability (Reim et al, 2018). However, our laboratory tests were not designed to test for dispersal, so any conclusions with regard to dispersal in real landscapes should be drawn carefully.…”

Anthropogenic and natural barriers affect genetic connectivity in an Alpine butterfly

“…This suggests that at least some individuals are highly mobile and have the potential to disperse over long distances, although Lycaena species are among the least mobile butterfly species (Ricketts, 2001). Note that we exclusively sampled males, while females are often the more dispersive sex in butterflies (Fischer et al., 1999; Hanski et al., 2004; Reim et al., 2018). This, however, should not affect results based on genetic relatedness in a sexually reproducing organism.…”

Local predation risk and matrix permeability interact to shape movement strategy

“…In addition, similar experimental approach, i.e. creation of habitat variability in small-sized outdoor mesocosms, has proven powerful to study the local determinants of emigration decisions in other small animals (Trochet et al 2013;Legrand et al 2015;Reim et al 2018). In this study, at first glance, the matrix type had no effect on toad's willingness to move.…”