Effects of habitat restoration on the morphology and life history traits of a rare wetland butterfly

Habitat restoration is commonly employed in endangered species conservation, but the resulting effect on recovery of vulnerable insect species has been mixed.  This is in part because the success of restoration efforts is evaluated by the recovery of vegetation structure and diversity, with the assumption that insect herbivores will recover following the restoration of their host plants.  Host plant quality of restored vegetation, however, may be either improved or degraded, with beneficial or detrimental effects on herbivore fitness.  Here, we assessed the impact of restoration on the adult morphology and female fitness of the locally declining Appalachian Brown butterfly (Satyrodes appalachia) in wetlands at Ft. Bragg military base in North Carolina. We reared Appalachian Brown larvae in field cages in experimental-restored wetland plots and measured the wing length and weight of the newly-emerged adults.  We then dissected females to evaluate the effect of restoration on their potential fecundity, and conducted a capture-mark-recapture study to understand the impact of differences in adult morphology on dispersal.  We predicted that in plots where host plant quality was poor, resource allocation would promote dispersal as opposed to fecundity, and the opposite would be true in plots with high host plant quality.

We found that restoration treatment significantly altered the allometric relationship between mass and wing length, and this effect differed by sex. Restoration treatment did not affect females’ potential fecundity, but females emerging from plots with trees had a greater number of mature eggs compared to females from plots with trees removed. Restoration treatments significantly affected male weight, with the heaviest males emerging from plots that had been restored to open wetland, similar to the butterflies’ natural breeding habitat.  Our capture-mark-recapture study demonstrated that an individual’s dispersal probability depended on its weight, sex, and the degree of habitat flooding.  Habitat restoration, through changes in plant quality, appears to directly alter adult morphology, which in turn alters the likelihood that an individual will disperse.