Population demography of alpine butterflies: Boloria pales and Boloria napaea (Lepidoptera: Nymphalidae) and their specific adaptations to high mountain environments

摘要

AbstractHigh mountain ecosystems are extreme habitats, and adaptation strategies to this ecosystem are still poorly understood in most groups. To unravel such strategies, we performed a MRR study in the Hohe Tauern National Park (Salzburg, Austria) with two nymphalid butterfly species,Boloria palesandB.?napaea. We analysed their population structure over one flight period by studying the development of population size and wing wear.B.?paleshad more individuals and a higher survival probability thanB.?napaea; the sensitivity to extreme weather conditions or other external influences was higher inB.?napaea. We only observed proterandry inB.?pales. Imagines of both species survived under snow for at least some days. Additionally, we observed a kind of risk-spreading, in that individuals of both species, and especiallyB.?pales, have regularly emerged throughout the flight period. This emergence pattern divided the population's age structure into three phases: an initial phase with decreasing wing quality (emergence?>?mortality), followed by an equilibrium phase with mostly constant average wing condition (emergence?=?mortality) and a final ageing phase with strongly deteriorating wing condition (mortality???emergence). Consequently, neither species would likely become extinct because of particularly unsuitable weather conditions during a single flight period. The observed differences between the two species suggest a better regional adaptation ofB.?pales, which is restricted to high m