Data from: Cold nights, city lights: artificial light at night reduces photoperiodically induced diapause in urban and rural populations of Aedes albopictus

As the planet becomes increasingly urbanized, it is imperative that we understand the ecological and evolutionary consequences of urbanization on species. One common attribute of urbanization that differs from rural areas is the prevalence of artificial light at night (ALAN). For many species, light is one of the most important and reliable environmental cues, largely governing the timing of daily and seasonal activity patterns. Recently, it has been shown that ALAN can alter behavioral, phenological, and physiological traits in diverse taxa. For temperate insects, diapause is an essential trait for winter survival and commences in response to declining daylight hours in the fall. Diapause is under strong selection pressure in the mosquito, Aedes albopictus; local adaptation and rapid evolution has been observed along a latitudinal cline. It is unknown how ALAN affects this photosensitive trait or if local adaptation has occurred along an urbanization gradient. Using a common garden experiment, we experimentally demonstrated that simulated ALAN reduces diapause incidence in this species by as much as 40%. There was no difference, however, between urban and rural demes. We also calculated diapause incidence from wild demes in urban areas to determine if wild populations exhibited lower than predicted incidence compared to estimates from total nocturnal darkness. In early fall, lower than predicted diapause incidence was recorded but all demes reached nearly 100% diapause before terminating egg laying. It is possible that nocturnal resting behavior in vegetation limits the amount of ALAN exposure this species experiences potentially limiting local adaptation.

随着全球城市化进程持续推进，解析城市化对物种产生的生态与进化影响已成为至关重要的研究方向。城市化与乡村区域的一项典型差异，在于夜间人工光（artificial light at night, ALAN）的广泛分布。对于多数物种而言，光是最为关键且可靠的环境线索之一，在很大程度上调控着每日与季节性活动节律的时间节点。近期研究表明，夜间人工光能够改变多个生物类群的行为、物候与生理性状。对于温带昆虫来说，滞育是其越冬存活的核心适应性性状，通常会在秋季昼长逐步缩短时启动。白纹伊蚊（Aedes albopictus）的滞育过程承受着极强的选择压力，研究人员已在其纬度梯度中观测到局部适应与快速进化现象。目前尚不明确夜间人工光会对这一光敏感性状产生何种影响，也不清楚沿城市化梯度是否会出现该性状的局部适应。本研究通过同质园实验（common garden experiment），以受控实验证实：模拟夜间人工光可使该物种的滞育发生率降低最高达40%。但城市与乡村同类群之间并未出现显著差异。我们还对城市区域的野生同类群的滞育发生率进行了测算，以对比全黑夜环境下的预估数值，探究野生种群的滞育发生率是否低于预期。在初秋时节，实测的滞育发生率确实低于预估水平，但所有同类群在停止产卵前均达到了近100%的滞育率。该物种或可通过在植被中进行夜间栖息的行为，限制自身接触夜间人工光的程度，这有可能阻碍局部适应的发生。