Data from: Implications of a temperature increase for host plant range: predictions for a butterfly

Although changes in phenology and species associations are relatively well-documented responses to global warming, the potential interactions between these phenomena are less well understood. In this study, we investigate the interactions between temperature, phenology (in terms of seasonal timing of larval growth) and host plant use in the polyphagous butterfly Polygonia c-album. We found that the hierarchy of larval performance on three natural host plants was not modified by a temperature increase as such. However, larval performance on each host plant and temperature treatment was affected by rearing season. Even though larvae performed better at the higher temperature regardless of the time of the rearing, relative differences between host plants changed with the season. For larvae reared late in the season, performance was always better on the herbaceous plant than on the woody plants. In this species, it is likely that a prolonged warming will lead to a shift from univoltinism to bivoltinism. The demonstrated interaction between host plant suitability and season means that such a shift is likely to lead to a shift in selective regime, favoring specialization on the herbaceous host. Based on our result, we suggest that host range evolution in response to temperature increase would in this species be highly contingent on whether the population undergoes a predicted shift from one to two generations. We discuss the effect of global warming on species associations and the outcome of asynchrony in rates of phenological change.尽管物候变化（phenology）与物种间关联（species associations）作为全球变暖（global warming）的响应已有较多研究佐证，但二者间的潜在互作机制仍缺乏充分认知。本研究以多食性蛱蝶白纹黄蛱蝶（Polygonia c-album）为对象，探究温度、物候（以幼虫生长的季节时序为表征）与寄主植物利用之间的互作关系。研究发现，三种天然寄主植物上的幼虫适合度表现等级排序本身并未因温度升高而改变。然而，各寄主植物及温度处理组下的幼虫适合度表现均受饲养季的影响。尽管无论饲养时段如何，幼虫在更高温度下的适合度均更佳，但寄主植物间的相对适合度差异随饲养季发生变化。对于后期饲养的幼虫而言，其在草本植物上的适合度始终优于木本植物。该物种很可能因长期变暖而从一化性（univoltinism）转变为二化性（bivoltinism）。已证实的寄主植物适合度与饲养季的互作关系表明，这种世代数转变将引发选择机制的改变，更倾向于选择对草本寄主的专化。基于本研究结果，我们提出：该物种的寄主范围演化对温度升高的响应，高度取决于种群是否会发生预期的从1代到2代的世代数转变。我们还探讨了全球变暖对物种间关联的影响，以及物候变化速率异步性所带来的生态结果。