Life-cycle regulation and life history plasticity in the speckled wood butterfly: are reaction norms predictable?
Article first published online: 14 JAN 2008
Biological Journal of the Linnean Society
Volume 55, Issue 2, pages 143–157, June 1995
How to Cite
NYLIN, S., WICKMAN, P.-O. and WIKLUND, C. (1995), Life-cycle regulation and life history plasticity in the speckled wood butterfly: are reaction norms predictable?. Biological Journal of the Linnean Society, 55: 143–157. doi: 10.1111/j.1095-8312.1995.tb01056.x
- Issue published online: 14 JAN 2008
- Article first published online: 14 JAN 2008
- Received 25 February 1'994; accepted for publication 5 October 1994
- reaction norms;
- diapause -growth;
- Pararge aegeria;
We investigated whether interpopulational variation in life-cycle regulation and life-history plasticity, in response to photoperiod, is predictable from considerations of what would be the adaptive life cycle and life history in a given environment. The investigation was performed on five populations of the speckled wood butterfly, Pararge aegeria (L.) (Lepidoptera: Nymphalidae), from central and south Sweden, England, Spain and Madeira. Insects from all five populations were reared at all daylengths from 10 h to 20 h at 17oC. Larval and pupal development times were noted. Predictions were met regarding the type of life-cycle regulation and the shape of reaction norms. Evidence for diapause (larval summer and winter diapause, pupal winter diapause) was found in the three northern populations (P. a. tircis) but not in the two southern populations (P. a. aegeria). Photoperiodic thresholds for diapause induction followed the predicted latitudinal patterns, and this was also the case regarding quantitative regulation of development time (by photoperiod) among directly developing individuals. Under direct development, development time was progressively shorter in shorter daylengms in the two Swedish populations, where this signals progressively later dates. This was not found in the English, Spanish and Madeiran populations where such a response is likely to be maladaptive, because one or more generations of larvae are present before summer solstice. There were also unexpected results, for which we propose preliminary adaptive explanations.