Fatty acids (FAs) are key nutrients for fitness which take part in multiple physiological processes over the ontogeny of organisms. Yet, we lack evidence on how FA nutrition mediates life-history trade-offs and ontogenetic niche shifts in natural populations. In a field study, we analyzed ontogenetic changes in the FAs of Eurasian perch (Perca fluviatilis L.), a widespread fish that goes through ontogenetic niche shifts and can have high individual niche specialization. Diet explained most of the variation in the FA composition of perch dorsal muscle over early ontogeny (28%), while the total length explained 23%, suggesting that perch significantly regulated FA composition over early ontogeny. Condition explained 1% of the remaining variation. 18:3n-3 (ALA) and 18:4n-3 (SDA) indicated planktivory; 18:1n-7, benthivory; and 22:6n-3 (DHA), piscivory in perch diet. Conversely, perch regulated long-chained polyunsaturated fatty acids (PUFAs), such as 20:5n-3 (EPA), 20:4n-6 (ARA) and 22:6n-3 (DHA) over ontogeny, emphasizing the role of such FAs in early growth and sexual maturation. Adult perch increasingly retained 16:1n-7 and 18:1n-9 suggesting higher energy storage in older perch. Furthermore, differences in DHA availability in diet correlated with intra-cohort differences in perch growth, potentially hindering the overall use of benthic resources and promoting earlier shifts to piscivory in littoral habitats. Overall, this study indicates that in addition to diet, internal regulation may be more important for FA composition than previously thought. Differences between FA needs and FA availability may lead to life-history trade-offs that affect the ecology of consumers, including their niche.

中文翻译：

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与普通水生消费者的个体发育变化和生态位分化有关的脂肪酸组成调节。

脂肪酸（FAs）是健身的关键营养素，它参与了生物体发育过程中的多个生理过程。然而，我们缺乏关于FA营养如何介导自然种群中生命历史权衡和个体生态位转变的证据。在一项野外研究中，我们分析了欧亚鲈（Perca fluviatilis L.）的FA的个体发育变化，这是一条经历个体生态位转移并具有较高个体生态位专长的鱼类。Diet解释了早期个体发育中鲈鱼背肌FA成分的大部分变化（28％），而全长解释了23％，表明鲈鱼显着调节了早期个体发育的FA成分。条件解释了剩余变化的1％。18：3n-3（ALA）和18：4n-3（SDA）表示浮游生物；18：1n-7，底栖动物；22：6n-3（DHA），鲈鱼饮食中的食肉动物。相反，在个体发育过程中，栖息着受调节的长链多不饱和脂肪酸（PUFA），例如20：5n-3（EPA），20：4n-6（ARA）和22：6n-3（DHA），强调了这种作用早期生长和性成熟中的FA。成年鲈鱼越来越多地保留16：1n-7和18：1n-9，这表明老年鲈鱼的能量存储量更高。此外，饮食中DHA可用性的差异与队列内鲈鱼生长的差异相关，有可能阻碍底栖资源的整体利用并促进沿岸生境早期转移到食肉动物。总体而言，这项研究表明，除了饮食外，内部调节对于FA组成可能比以前认为的更为重要。FA需求和FA可用性之间的差异可能会导致生命历史权衡，从而影响消费者的生态，