response of two butterfly species to climatic variation at the edge of their range and the implications for poleward range shifts

• Published in: Oecologia 2008-10, Vol.157 (4), p.583-592
• Main Authors: Hellmann, Jessica J, Pelini, Shannon L, Prior, Kirsten M, Dzurisin, Jason D. K
• Format: Article
• Language: English
• Subjects: Acclimatization; Altitude; Animal and plant ecology; Animal, plant and microbial ecology; Animals; Biological and medical sciences; Biomedical and Life Sciences; British Columbia; Butterflies; Butterflies & moths; Butterflies - physiology; Climate; Climate change; Climate models; Ecological genetics; Ecology; Ecosystem; Fundamental and applied biological sciences. Psychology; General aspects; Host plants; Hydrology/Water Resources; Insect ecology; Insect larvae; Insecta; Invertebrates; Larvae; Life Sciences; Plant Sciences; Population decline; Population Density; Population Dynamics; Population ecology; Population Ecology - Original Paper; Population Ecology - Original Papers; Species; Species Specificity; Temperature; Translocation
• ISSN: 0029-8549; 1432-1939
• DOI: 10.1007/s00442-008-1112-0

To predict changes in species' distributions due to climate change we must understand populations at the poleward edge of species' ranges. Ecologists generally expect range shifts under climate change caused by the expansion of edge populations as peripheral conditions increasingly resemble the range core. We tested whether peripheral populations of two contrasting butterflies, a small-bodied specialist (Erynnis propertius) and a large-bodied generalist (Papilio zelicaon), respond favorably to warmer conditions. Performance of populations related to climate was evaluated in seven peripheral populations spanning 1.2° latitude (160 km) using: (1) population density surveys, an indirect measure of site suitability; and (2) organismal fitness in translocation experiments. There was evidence that population density increased with temperature for P. zelicaon whose population density declined with latitude in 1 of 3 sample years. On the other hand, E. propertius showed a positive relationship of population density with latitude, apparently unrelated to climate or measured habitat variables. Translocation experiments showed increased larval production at increased temperatures for both species, and in P. zelicaon, larval production also increased under drier conditions. These findings suggest that both species may increase at their range edge with warming but the preference for core-like conditions may be stronger in P. zelicaon. Further, populations of E. propertius at the range boundary may be large enough to act as sources of colonists for range expansions, but range expansion in this species may be prevented by a lack of available host plants further north. In total, the species appear to respond differently to climate and other factors that vary latitudinally, factors that will likely affect poleward expansion.