The adaptive value of energy storage and capital breeding in seasonal environments
The adaptive value of energy storage and capital breeding in seasonal environments
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季节环境下储能与资本培育的适应性价值
DOI：
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发表时间：
2009
期刊：
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通讯作者：
Ø. Fiksen
中科院分区：
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作者：
Ø. Varpe;C. Jørgensen;G. Tarling;Ø. Fiksen
在季节周期中繁殖的时间是一种具有重要适应性后果的生活史特征。资本育种者从储存的资源中产生后代，通过将喂养和繁殖分离，可能会改变食物或捕食季节性造成的限制。而收益育种则是同时采食繁殖后代，其缺点是灵活性较差，但效率较高，没有携带物料的库存成本。在这里，我们评估了居住在季节性高纬度环境中的草食性浮游动物的资本和收入繁殖的相对盈利能力。我们应用一个状态依赖的生活史模型，其中生殖值用于优化全年的能量分配和滞育策略。模拟了三种环境情景：早期、中期和晚期的摄食季节。我们发现，资本育种在季初最为重要。资本育种占所产卵的7-9%，但由于早期卵的繁殖价值高，按繁殖价值衡量，资本育种占9-30%。资本育种的主要好处是在饲养季节之前繁殖-当蛋的繁殖价值达到顶峰时。此外，资本育种也被用于在收入育种时期提高产蛋率。对于出生晚于季节的个体，该模型预测的生命周期为两年，而不是典型的一年一次的生命周期。这些个体可以在第二年获得早期繁殖和资本育种的好处，而不是在第一年晚些时候进行收入育种。我们强调从完整生命周期的角度评估资本和收入育种等生殖策略的重要性。特别是，了解后代适应性的季节性对于理解资本繁殖的进化和种群水平的后果至关重要。
Timing of reproduction in a seasonal cycle is a life history trait with important fitness consequences. Capital breeders produce offspring from stored resources and, by decoupling feeding and reproduction, may bend the constraints caused by seasonality in food or predation. Income breeders, on the other hand, produce offspring from concurrent food intake, with the disadvantage of less flexibility, but with high efficiency and no inventory costs of carrying stores. Here, we assess relative profitability of capital and income breeding in herbivorous zooplankton inhabiting seasonal, high-latitude environments. We apply a state-dependent life history model where reproductive values are used to optimise energy allocation and diapause strategies over the year. Three environmental scenarios were modelled: an early, an intermediate, and a late feeding season. We found that capital breeding was most important in the early season. Capital breeding ranged from 7-9% of the eggs produced but, because of the high reproductive value of early eggs, capital breeding ranged from 9-30% when measured in terms of reproductive value. The main benefit of capital breeding was reproduction prior to the feeding season - when the reproductive value of an egg peaked. In addition, capital breeding was also used to increase egg production rates at times of income breeding. For individuals born late in the season the model predicted a two-year cycle instead of the typical annual life cycle. These individuals could then reap the benefits of early reproduction and capital breeding in their second year instead of income breeding late in the first year. We emphasize the importance of evaluating reproductive strategies such as capital and income breeding from a complete life cycle perspective. In particular, knowing the seasonality in offspring fitness is essential to appreciate evolutionary and population-level consequences of capital breeding.