775 / 2024-09-19 12:30:41

Adaptive responses of water flea to artificial light at night revealed through dormant egg bank in a coastal city sediment

rapid evolution,urbanization,artificial light at night,dormant egg,Cladocera

Rapid urbanization has dramatically transformed natural environments, with artificial light at night (ALAN)—a defining feature of urban areas—introducing novel challenges to ecosystems. Dormant egg bank, functioning as "time capsules" that preserve genetic diversity and population history, provide valuable insights into the evolutionary pressures exerted by ALAN over time. Shanghai, a coastal megacity in China, with its unique geographical and urban characteristics, provides an ideal setting to explore the adaptive evolution of zooplankton in response to ALAN. In this study, we resurrected dormant eggs of Ceriodaphnia cornuta (Cladocera) from various historical periods and employed a common garden experiment to assess the morphological and life-history responses to two ALAN treatments: white light and colored light. Our results indicate that ALAN significantly suppressed Ceriodaphnia reproduction, although this inhibitory effect lessened in more recent historical populations. Moreover, compared to white light, colored light exerted a substantially weaker negative impact. The effect size for body length at sexual maturity also increased consistently in populations closer to the present day. Conversely, eye development remained relatively stable across light treatments, showing no marked temporal variation. These findings enhance our understanding of urbanization’s influence on adaptive evolution and provide a foundation for the informed management and regulation of artificial lighting in urban ecosystems.