Climate change and habitat associations at species' range boundaries

摘要: Species are more restricted in their habitat associations at leading-edge range margins where climatic conditions marginal. Hence they predicted to broaden these locations as the climate warms, potentially increasing availability and rates of expansion. I analysed long-term distribution records (collected by volunteers) abundance data (UK Butterfly Monitoring Scheme transect data) investigate how host plant two butterfly species that reach Britain have changed over 40 years warming. The speckled wood (Pararge aegeria) is primarily associated with woodland but its vary spatially temporally. found this has a weaker association warmer parts Britain, particularly regions warm wet summers. Over time, occurrence outside increased most summer winter temperatures rainfall most. Field experiments showed larval performance poorer open (grassland) than closed (woodland) habitats, microclimatic differences between habitats. Thus conclude slower population growth play an important role driving observed variation associations. brown argus (Aricia agestis) was previously using rockrose (Helianthemum nummularium) which grows microclimates. shown summers allowed it increase use Geraniaceae species, occur cooler locations. widespread so substantially for butterfly, leading extremely rapid expansion species. broadening response change, resulting substantial increases