Most organisms reproduce in a dynamic environment, and life-history theory predicts that this can favor the evolution of strategies that capitalize on good times and avoid bad times. When offspring experience these environmental changes, fitness can depend strongly upon environmental conditions at birth and at later life stages. Consequently, fitness will be influenced by the reproductive decisions of parents (i.e., birthdate effects) and developmental decisions (e.g., adaptive plasticity) of their offspring. We explored the consequences of these decisions using a highly iteroparous coral reef fish (the sixbar wrasse, Thalassoma hardwicke), and in a system where both parental and offspring environments vary with the lunar cycle. We tested the hypotheses that (1) reproductive patterns and offspring survival vary across the lunar cycle and (2) offspring exhibit adaptive plasticity in development time. We evaluated temporal variation in egg production from Feb-June 2017, and corresponding larval developmental histories (inferred from otolith microstructure) of successful settlers and surviving juveniles that were spawned during that same period. We documented lunar-cyclic variation in egg production (most eggs were spawned at the new moon). This pattern was at odds with the distribution of birthdates of settlers and surviving juveniles -- most individuals that successfully survived to settlement and older stages were born during the full moon. Consequently, the probability of survival across the larval stage was greatest for offspring born close to the full moon, when egg production was at its lowest. Offspring also exhibited plasticity in developmental duration, adjusting their age at settlement to settle during darker portions of the lunar cycle than expected given their birthdate. Offspring born near the new moon tended to be older and larger at settlement, and these traits conveyed a strong fitness advantage (i.e., a carry-over effect) through to adulthood. We speculate that these effects (1) are shaped by a dynamic landscape of risk and reward determined by moonlight, which differentially influences adults and offspring, and (2) can explain the evolution of extreme iteroparity in sixbars.

中文翻译：

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整个月球周期的生殖物候：父母的决定、后代的反应以及对珊瑚鱼的影响

大多数生物在动态环境中繁殖，生命史理论预测，这有利于利用好时光并避免坏时光的策略的进化。当后代经历这些环境变化时，健康状况在很大程度上取决于出生时和生命后期阶段的环境条件。因此，适应性将受到父母的生殖决定（即出生日期效应）和后代的发育决定（例如适应性可塑性）的影响。我们使用高度迭代繁殖的珊瑚礁鱼（六条濑鱼，Thalassoma hardwicke）以及在父母和后代环境随月球周期变化的系统中探索了这些决定的后果。我们测试了以下假设：(1) 生殖模式和后代存活率在整个月球周期中有所不同，(2) 后代在发育时间表现出适应性可塑性。我们评估了 2017 年 2 月至 6 月产蛋量的时间变化，以及同期产卵的成功定居者和幸存幼虫的相应幼虫发育历史（从耳石微观结构推断）。我们记录了鸡蛋产量的月球周期变化（大多数鸡蛋在新月产卵）。这种模式与定居者和幸存的幼鱼的出生日期分布不一致——大多数成功存活到定居点和较老阶段的个体都是在满月期间出生的。因此，接近满月出生的后代在幼虫阶段存活的可能性最大，产蛋量最低的时候。后代在发育期间也表现出可塑性，调整他们的定居年龄，以在比预期的出生日期更暗的月球周期阶段定居。在新月附近出生的后代在定居时往往年龄更大、体型更大，并且这些特征传递到成年期的强大健康优势（即，延续效应）。我们推测，这些影响 (1) 是由月光决定的风险和回报的动态景观塑造的，月光对成年人和后代的影响不同，并且 (2) 可以解释六边形中极端迭代的演变。在新月附近出生的后代在定居时往往年龄更大、体型更大，并且这些特征传递到成年期的强大健康优势（即，延续效应）。我们推测，这些影响 (1) 是由月光决定的风险和回报的动态景观塑造的，月光对成年人和后代的影响不同，并且 (2) 可以解释六边形中极端迭代的演变。在新月附近出生的后代在定居时往往年龄更大、体型更大，并且这些特征传递到成年期的强大健康优势（即，延续效应）。我们推测，这些影响 (1) 是由月光决定的风险和回报的动态景观塑造的，月光对成年人和后代的影响不同，并且 (2) 可以解释六边形中极端迭代的演变。