ABSTRACT: The horseshoe crab Limulus polyphemus exhibits rhythmic locomotor behavior that is controlled by both internal clocks and external tidal cycles. Recent findings demonstrate that adult horseshoe crabs from a 2 tides d^-1 environment usually express 2 bouts of activity d^-1, while adults from areas with 1 dominant tide d^-1, or with negligible tides (atidal), generally express 1 bout of activity d^-1. Horseshoe crabs from these different environments are genetically distinct, so it is not known if these behavioral differences are driven by genetics or by the tides they experience early in life. To address this question, freshly spawned horseshoe crab eggs from populations that experience these 3 distinct environmental tidal regimes were reared in the laboratory under 1 of the above 3 artificial tidal conditions. Then the activity of individual larval and 2^nd instar juveniles was recorded over 3 wk using video tracking software. Endogenous circatidal rhythms were present in most (88/108) of the freshly molted juveniles from all 3 populations, even when they were raised in atidal conditions, indicating a strong genetic influence. To our knowledge, this is the first demonstration of the presence of genetically driven endogenous circatidal rhythms in an individual juvenile marine organism. Nevertheless, the early environment was also capable of having an impact, because it significantly affected rhythm expression in crabs in the 1 tide d^-1 population. Thus, overall, the tidal environment to which horseshoe crab eggs are exposed during development appears to have less of an influence than genetics on their expression of tidal rhythms of locomotion.

中文翻译：

---

自然与营养对美洲horse蟹Li的轮转节律表达的相对影响

摘要：The蟹多poly属动物的节律性运动行为受内部时钟和外部潮汐周期的控制。最近的发现表明，在2潮d ^-1环境中的成年horse通常表达2轮活动d ^-1，而在1潮汐d ^-1或潮汐可忽略的地区（成潮）的成年generally通常表达1轮。活动d ^-1。来自这些不同环境的蟹在遗传上是不同的，因此尚不清楚这些行为差异是否是由遗传或它们早年经历的潮汐驱动的。为了解决这个问题，在上述3种人工潮汐条件中的1种中，在实验室中饲养了经历了这3种不同环境潮汐制度的种群的新鲜产生的horse蟹卵。然后是幼虫的活动和^第二使用视频跟踪软件在3周内记录了成年幼体。来自所有3个种群的大多数刚蜕变的幼体中都存在内源性的昼夜节律，即使它们是在干旱条件下长大的，也表明它们具有很强的遗传影响力（88/108）。据我们所知，这是单个海洋生物个体中遗传驱动的内源性旋回节律的首次证明。但是，早期环境也能够产生影响，因为它会显着影响1潮d ^-1种群中蟹的节律表达。因此，总的来说，马蹄蟹卵在发育过程中所接触的潮汐环境似乎对它们的运动潮汐表达的影响小于遗传学。