Resource grain scales mobility and adult morphology in butterflies (original) (raw)

Relations between species mobility and life history traits and/or landscape and habitat features are of broad interest to ecologists and conservation biologists. Here we investigated the reliability of the relations between mobility and (1) resource grain and (2) morphological traits in butterflies. Results were used to assess the biological realism of morphological traits associated with flight as mobility proxies. We then investigated how biological, environmental and landscape variables affected these mobility proxies. We used a multi-species approach on two different sites. Morphological traits were measured on ca. 20 individuals per site, species and sex. Resource distribution was carefully monitored by investigating the spatial distribution and overlap of larval and adult feeding resources, together representing the resource grain. The spatial extent of individual station keeping movements was estimated from distances recorded between successive recaptures of individuals from mark-release-recapture experiments. Morphological traits seemed reliable proxies of mobility, as both variables were strongly correlated. Morphological variations were related to flight type and spatial dimension of nectar resource. The most striking point was the clear relation between the index of relative investment in mobility versus fecundity in females with the spatial dimension of adult feeding resource. Given the generally accepted relation between abdomen volume and female fecundity, this suggests that females might invest more in fecundity when nectar resources are widespread. Finally, we did not detected effects of landscape structure on mobility, which indicates that functional grain of resources is more likely to influence mobility and evolution of morphology in butterflies than landscape connectivity.