DANKS, H.V.; Canadian Museum of Nature, Ottawa, ON: Seasonal adaptations in arctic insects

Many insect species with a wide range of adaptations to seasonality live in the arctic. Long, cold winters are met, for example, by cold hardiness including widespread tolerance to freezing and by the choice of protected overwintering sites. Adaptations to short, cool summers include activity at low temperatures, selection of warm habitats, melanism and hairiness coupled with basking behavior, and either prolonged or abbreviated life cycles. Diapause and other life-cycle traits ensure that many species emerge as early as possible in the short summer, with brief synchronized reproduction that maximizes the time for offspring development before winter returns. Some species overwinter in sites that thaw earliest in spring, even if they are relatively exposed in winter. Other adaptations respond to year-to-year variability, such as prolonged diapause in some individuals that provides insurance against unsuitable summers. All of these adaptations are co-ordinated. For example, cold hardiness relies not only on several types of physiological adjustments, but also on habitat choice and timing. Because the adaptations are complex and finely tuned to the particular conditions, predicted climatic warming probably will have unexpected effects. In particular, an increase in air temperatures might enhance summer cloud cover as sea ice melts and would thus serve to reduce temperatures for insect development and activity, because sunshine provides critical warmth to insects and their microhabitats. The complexity of the current and potential responses of insects to arctic conditions means that research on insect adaptations must be done in sufficient detail.