The timing of reproduction is often governed by environmental variables, such as temperature or rainfall. Understanding how environmental variables affect mating dynamics is necessary to predict how systems and populations may adapt to changing environmental conditions and is crucial for management of threatened species. The American horseshoe crab (Limulus polyphemus) ranges from the Yucatan to Maine in distinct populations that differ in their timing of reproduction; while most populations have only one breeding period during the spring, some southern populations have two breeding periods. Here we discuss seasonal patterns of reproduction in a Florida Gulf coast population where horseshoe crabs have two periods of breeding: one in the spring and another in the fall. We used environmental measurements, spawning surveys, mark-recapture, and measurements of adult traits and spawning behavior to compare reproductive parameters between the two spawning seasons over three years. We then evaluated whether environmental conditions affect fall and spring horseshoe crab nesting patterns similarly and whether fall and spring horseshoe crabs should be considered two separate populations. We found significant differences in environmental conditions across seasons and in a wide variety of horseshoe crab traits and nesting parameters. Furthermore, environmental conditions affected nesting behaviors of fall and spring horseshoe crabs differently. However, some individuals spawn during both seasons, suggesting that trait differences may be attributable to environmental effects during development or seasonal plasticity, rather than genetic differences, although further study is necessary. Finally, our results suggest that management practices should be tailored to each population, because environmental conditions may have different effects even on genetically similar groups.

中文翻译：

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佛罗里达州墨西哥湾沿岸马蹄蟹（鲎）繁殖的季节性变化

繁殖的时间通常受环境变量的控制，例如温度或降雨量。了解环境变量如何影响交配动态对于预测系统和种群如何适应不断变化的环境条件是必要的，并且对于受威胁物种的管理至关重要。美国鲎 (Limulus polyphemus) 从尤卡坦半岛到缅因州分布在不同的种群中，它们的繁殖时间不同；虽然大多数种群在春季只有一个繁殖期，但一些南方种群有两个繁殖期。在这里，我们讨论佛罗里达墨西哥湾沿岸种群的季节性繁殖模式，马蹄蟹有两个繁殖期：一个在春季，另一个在秋季。我们使用环境测量、产卵调查、标记重新捕获、并测量成虫性状和产卵行为，以比较三年内两个产卵季节之间的繁殖参数。然后，我们评估了环境条件是否会类似地影响秋季和春季马蹄蟹的筑巢模式，以及是否应将秋季和春季马蹄蟹视为两个独立的种群。我们发现不同季节的环境条件以及各种鲎性状和筑巢参数存在显着差异。此外，环境条件对秋季和春季马蹄蟹的筑巢行为有不同的影响。然而，一些个体在两个季节都产卵，这表明性状差异可能归因于发育过程中的环境影响或季节性可塑性，而不是遗传差异，尽管需要进一步研究。