Mechanistic and evolutionary aspects of light-induced dormancy termination in a temporary pond crustacean
Mechanistic and evolutionary aspects of light-induced dormancy termination in a temporary pond crustacean
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临时池塘甲壳类动物光诱导休眠终止的机制和进化方面
DOI：
10.1899/12.157.1
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发表时间：
2013
期刊：
影响因子：
--
通讯作者：
L. Brendonck
中科院分区：
文献类型：
--
作者：
Tom Pinceel;B. Vanschoenwinkel;Joeri Uten;L. Brendonck
抽象的。大多数淡水浮游动物物种产生休眠卵或其他长寿的抵抗生命阶段，以过渡不适合生长和繁殖的时期。决定这些休眠阶段激活的主要线索之一是光照。与植物种子萌发的类似过程相反，对淡水浮游动物的光激活机制及其潜在的适应价值知之甚少。我们利用一个临时池模型，调查孵化响应的仙女虾Branchipodopsis wolfi的休眠蛋的一组特定的选定的光制度，并评估的重要性，鸡蛋色素调节对光的线索的敏感性。我们的研究结果表明存在一个临界光阈值激活导致最大孵化。此外，光激活的过程似乎不是纯粹的累积，因为在单个连续脉冲中给予的光导致比在几个2小时脉冲中给予的相同量的光高得多的孵化。最后，深色的鸡蛋比浅色的鸡蛋对光照不太敏感，导致在实验性洪水期间深色鸡蛋的孵化延迟。这一结果表明，鸡蛋色素沉着的自然变化可能是一种风险扩散机制，在营养有限的条件下，通常在洪水早期流行的死亡率的风险，一方面，过早的池塘干燥的死亡率的风险，另一方面，权衡亲属竞争造成的死亡率的风险。总体而言，我们的研究结果表明，光能激活阈值和蛋壳的色素沉着的变化可能是重要的特征，可能有助于浮游动物谱系之间的孵化物候变化。
Abstract. Most freshwater zooplankton species produce dormant eggs or other long-lived resistant life stages to bridge periods that are unsuitable for growth and reproduction. One of the principal cues that determine activation of these dormant stages is light exposure. Contrary to the analogous process of seed germination in plants, relatively little is known about the mechanism of light activation and its potential adaptive value in freshwater zooplankton. We made use of a temporary pool model to investigate the hatching response of resting eggs of the fairy shrimp Branchipodopsis wolfi to a specific set of selected light regimes and to evaluate the importance of egg pigmentation for mediating susceptibility to light cues. Our results suggest the presence of a critical light threshold for activation leading to maximal hatching. Moreover, the process of light activation does not appear to be purely cumulative because light administered in a single continuous pulse resulted in much higher hatching than the same amount of light administered in several 2-h pulses. Last, darkly pigmented eggs were less sensitive than lightly pigmented eggs to light exposure, resulting in delayed hatching of darker eggs during an experimental inundation. This result indicates that natural variation in egg pigmentation could be a risk-spreading mechanism that trades off the risks of mortality caused by kin competition during the nutrient-limited conditions that typically prevail early during inundations on one hand and the risk of mortality from premature pond drying on the other hand. Overall, our results indicate that light-energy activation thresholds and variation in pigmentation of the eggshell can be important traits that may contribute to variation in hatching phenology among zooplankton lineages.