Rhythms of a changing ocean: Chronobiology and control of reproduction in marine organisms

生命及其节律是在海洋中进化的，然而我们对生物节律的理解主要围绕着陆地模型中的昼夜节律和季节周期。我对海洋生物的研究致力于阐明周期性生活史事件中的关键相互作用，遵循一种综合的观点，该观点结合了时间生物学(生物活动与时间之间的关系)、物候学(周期性事件与气候条件之间的关系)和进化生物学(生物节律的适应益处)的观点。我的长期目标是阐明底栖动物种群生殖周期的中介因素和适应意义。最近，我们发现6门24种北方物种经历了季节性和月球节律的繁殖，其大量产卵事件类似于珊瑚礁，尽管物种特有的昼夜成分保持了生殖隔离。我们还发现，深海物种可能暴露在很小的环境变异性中，仍然表现出季节性和月球繁殖周期。目前提出的节律性繁殖事件的机制和优势不能完全解释为什么如此多的物种在春季释放后代，无论繁殖模式(自由产卵、孵化)、幼虫类型(取食、不取食)、深度或区域。该计划的短期目标是：1)进一步研究深海物种的繁殖周期；2)比较不同生活史物种周期性繁殖的适应价值；3)梳理深海和北方类群繁殖节律的驱动因素；4)调查“哨兵”(更能接受环境提示的生物体)的概念；5)识别季节性繁殖物种的昼夜节律。通过整合生殖生物学、时间生物学和化学生态学的概念，我们希望理清生物钟、外部线索和社会相互作用各自所起的作用，并对底栖生态系统的功能有更好的了解。确定海洋类群多层次生物节律的驱动因素不仅有助于洞察我们的进化历史，还有助于发展水产养殖技术和基于时间尺度的管理和养护战略。

Life and its rhythms evolved in the sea, yet our understanding of biological rhythms largely revolves around circadian and seasonal cycles in terrestrial models. My research on marine organisms strives to elucidate key interplays in cyclic life-history events, following an integrated view that combines the perspectives of chronobiology (relation between biological activity and time), phenology (relation between periodic events and climatic conditions) and evolutionary biology (adaptive benefits of biological rhythms). My long-term objective is to clarify the mediators and adaptive significance of reproductive periodicities in benthic populations. Recently we found that 24 boreal species belonging to 6 phyla undergo seasonal and lunar rhythms of reproduction with mass-spawning events similar to coral reefs, although species-specific diel components preserve reproductive isolation. We also found that deep-sea species, presumably exposed to little environmental variability, still exhibit seasonal and lunar breeding cycles. Currently proposed mechanisms and advantages of rhythmic reproductive events cannot fully explain why so many species release progeny in spring, irrespective of reproductive mode (free spawning, brooding), larval type (feeding, nonfeeding), depth or region. The short term objectives of the proposed program are to: 1) further investigate breeding periodicity in deep-sea species; 2) compare the adaptive value of periodic reproduction in species with different life histories; 3) tease out the drivers of breeding rhythms in deep-sea and boreal taxa; 4) investigate the concept of "sentinels" (organisms more receptive to environmental cues); and 5) identify circadian rhythms in species with seasonal breeding. By integrating concepts of reproductive biology, chronobiology and chemical ecology we hope to disentangle the respective roles played by biological clocks, external cues and social interactions and gain a finer understanding of benthic ecosystem functioning. Identifying the drivers of multileveled biological rhythms in marine taxa will not only provide insight into our evolutionary past but also help develop aquaculture techniques and time-scale-based management and conservation strategies.