Changing demography and dispersal behaviour: ecological adaptations in an alpine butterfly

Abstract

High mountain ecosystems are extreme habitats for all organisms and therefore demand specific adaptations. In this context, we studied the ecology of the butterfly Euphydryas aurinia debilis in the High Tauern (Austria) and compared the obtained data against the ecology of the species in lower elevation habitats. We performed mark-release-recapture studies over the entire flight periods (end of June to end of July) in 2007 and 2008 to analyse the fundamental ecological parameters of a population. The demography of males and females was similar in both years, and no indication of typical protandry was detected. We observed a generally low dispersal of the individuals in both years, but males dispersed significantly more than females in 2008; this finding of low vagility was supported by allozyme analyses. Furthermore, butterflies survived periods of several days of continuously closed snow cover without any indication of increased mortality rates. In these three traits, this alpine population of E. aurinia apparently has ecological and physiological adaptations to the extreme requirements of high-altitude habitats and strongly deviates from the lower elevation populations.