Life-history plasticity in the butterfly Lycaena hippothoe:: local adaptations and trade-offs

Life-history theory predicts some cost to be associated with short development time, the most frequently assumed being small adult size. Alternatively, insects may increase developmental rates and grow fast to a larger size. Seasonal environments should select for phenotypic plasticity in growth and development, based on the need to complete development up to the diapausing stage before the onset of unfavourable season. Nevertheless, there must be some limit beyond which a compensation for a shorter development cannot be achieved. By comparing three geographically isolated populations of Lycaena hippothoe in common environments we show that in the Hungarian population development time seems to be traded off against size at maturity. This population is the only bivoltine one within this principally monovoltine species. Thus, realization of an additional generation per year, achieved through largely reduced development times, appears to carry the cost of substantially lower adult weights compared with other populations. In contrast, differences in development time in two monovoltine populations were not accompanied by a trade-off between development time and size. These results suggest that clear trade-offs are restricted to stressful situations, when compensation by an increase in growth rates is no longer feasible. We suggest the particularly short development time in the Hungarian population (facilitating a second generation), as well as the shorter development in an alpine (short vegetation period) compared with a western German population, to be adaptations to local climatic conditions. (C) 2002 The Linnean Society of London.