INRA-UMR ECOBIOP, Pôle d'Hydrobiologie INRA, 64310, Saint Pée sur Nivelle, France.
Oecologia. 2012 Feb;168(2):371-80. doi: 10.1007/s00442-011-2109-7. Epub 2011 Aug 25.
Ontogenetic niche shift should occur when the ratio of growth opportunities to mortality risk becomes higher in the subsequent habitat. While most studies have focused on size to understand the timing of these shifts, an endogenous factor like energetic status (interaction between energy available and energy requirements) appears as a natural candidate to integrate and analyze the growth trade-off between habitats. In this study, we measure energetic content and metabolic rate of individual brown trout (Salmo trutta) fry at emergence from gravel to investigate the influence of energetic status on the timing of this critical ontogenetic niche shift. In addition, as offspring energetic status is subject to parental effects, we examine how females could maximize their own fitness by influencing offspring emergence timing. Our results demonstrate that emergence from gravel is influenced by energetic status. Individuals that emerge first have a higher energetic content but deplete it faster because of a higher metabolic rate. We also find that female fecundity is positively related to emergence period duration. Moreover, our results suggest that females may decrease kin competition during the critical period of emergence by influencing the energetic status of offspring, thus, maximizing their own fitness. Our results help elucidate the mechanisms underlying early ontogenetic niche shifts in juvenile fish and suggest reasons why maternal investment can be so variable within populations.
当后续栖息地的生长机会与死亡率风险的比例变得更高时，个体发育生态位转移应该会发生。虽然大多数研究都关注体型来理解这些转变的时机，但像能量状态这样的内在因素（可用能量和能量需求之间的相互作用）似乎是整合和分析栖息地之间生长权衡的自然候选因素。在这项研究中，我们测量了刚从砾石中孵化出来的棕鳟 (Salmo trutta) 幼鱼的能量含量和代谢率，以研究能量状态对这一关键个体发育生态位转变时机的影响。此外，由于后代的能量状态受亲代效应的影响，我们研究了雌性如何通过影响后代的孵化时间来最大限度地提高自身适应性。我们的结果表明，砾石孵化受到能量状态的影响。首先孵化的个体具有更高的能量含量，但由于代谢率更高，它们会更快地消耗能量。我们还发现，雌性的繁殖力与孵化期持续时间呈正相关。此外，我们的结果表明，雌性可以通过影响后代的能量状态来减少关键孵化期的亲缘竞争，从而最大限度地提高自身适应性。我们的研究结果有助于阐明幼鱼早期个体发育生态位转变的机制，并为为什么母性投资在种群内会如此多变提供了原因。
