Department of Migration and Immuno-ecology, Max Planck Institute for Ornithology, Radolfzell 78479, Germany.
Proc Biol Sci. 2013 Jun 5;280(1763):20130593. doi: 10.1098/rspb.2013.0593. Print 2013 Jul 22.
To keep pace with progressing urbanization organisms must cope with extensive habitat change. Anthropogenic light and noise have modified differences between day and night, and may thereby interfere with circadian clocks. Urbanized species, such as birds, are known to advance their activity to early morning and night hours. We hypothesized that such modified activity patterns are reflected by properties of the endogenous circadian clock. Using automatic radio-telemetry, we tested this idea by comparing activity patterns of free-living forest and city European blackbirds (Turdus merula). We then recaptured the same individuals and recorded their activity under constant conditions. City birds started their activity earlier and had faster but less robust circadian oscillation of locomotor activity than forest conspecifics. Circadian period length predicted start of activity in the field, and this relationship was mainly explained by fast-paced and early-rising city birds. Although based on only two populations, our findings point to links between city life, chronotype and circadian phenotype in songbirds, and potentially in other organisms that colonize urban habitats, and highlight that urban environments can significantly modify biologically important rhythms in wild organisms.
为了跟上城市化的步伐，生物必须应对广泛的栖息地变化。人为的光和噪音改变了昼夜之间的差异，可能会干扰生物钟。众所周知，城市化的物种，如鸟类，会将它们的活动提前到清晨和夜间。我们假设这种经过修饰的活动模式反映了内源性生物钟的特性。我们使用自动无线电遥测技术，通过比较自由生活的森林和城市的欧洲画眉（Turdus merula）的活动模式来验证这一想法。然后，我们重新捕获了相同的个体，并在恒定条件下记录它们的活动。城市鸟类比森林同种鸟类更早开始活动，其运动活动的昼夜节律更快但不那么稳健。生物钟周期长度可以预测在野外的活动开始时间，这种关系主要是由节奏快且早起的城市鸟类决定的。尽管我们的研究结果仅基于两个种群，但它们指出了城市生活、生物钟和鸣禽的昼夜节律表型之间的联系，并且可能在其他栖息在城市环境中的生物中也存在联系，并强调城市环境可以显著改变野生生物中具有生物学重要意义的节律。
