Energy demand for reproduction leads to a wide diversity of foraging and life-history strategy among wild animals, linking to a common objective to maximize reproductive success. Semelparous squid species in particular can use up to 50% of the total energy intake for reproduction. However, the energy acquisition strategy for reproduction is still a controversial issue regarding whether the squid shift in diet ontogenetically. Here we used Argentinean shortfin squid (Illex argentinus) as a case study to investigate the strategy of energy acquisition for reproduction, by analyzing energy density of the squid’s reproductive tissues including ovary, nidamental glands and oviduct eggs, and stable isotopes and fatty acids of the squid’s ovary. The reproductive energy (the sum of the energy accumulated in ovary, nidamental glands and oviduct eggs) increased significantly with maturation. The ovary nitrogen stable isotopes (δ15N) showed a significant increase with maturation, but the increase by maturity stage was not equal to the typical enrichment of about 3‰ per trophic level. Isotopic niche width showed an increasing trend with maturation, and isotopic niche space exhibited greater overlap at advanced maturity stages. The relative amounts of 16:0, 20:5n3 and 20:4n6 in the ovary, tracing for carnivores and top predators, increased after the onset of maturation. The overall fatty acid profiles of the ovary showed significant differences among maturity stages, but obvious overlaps were found for mature squids. Mixed-effects model results revealed that reproductive energy was positively correlated with δ15N values. The reproductive energy was also positively related to the relative amounts of 18:0 and 20:4n6, respectively tracing for herbivores and top predators. Our results validate that the squid shifts to feed on higher trophic prey for reproduction as energy demand increases once maturation commences. However, the squid does not shift feeding habits at a trophic level but instead broadens prey spectrum, coupled with increasing intake of higher trophic prey items, to meet the energy demand for reproduction. Such energy acquisition strategy may be selected by the squid to maximize reproductive success by balancing energy intake and expenditure from foraging, warranting future studies that aim to clarify such strategy for reproduction among semelparous species.

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单产鱿鱼繁殖的能量获取策略

繁殖的能量需求导致野生动物的觅食和生活史策略多种多样，这与最大化繁殖成功率的共同目标有关。特别是半产鱿鱼物种可以使用高达 50% 的总能量摄入来进行繁殖。然而，繁殖的能量获取策略仍然是一个有争议的问题，即鱿鱼是否会个体遗传地改变饮食。本文以阿根廷短鳍乌贼 (Illex argentinus) 为例，通过分析乌贼卵巢、卵腺和输卵管卵等生殖组织的能量密度，以及乌贼的稳定同位素和脂肪酸，研究其繁殖的能量获取策略。鱿鱼的卵巢。生殖能量（卵巢中积累的能量总和，卵腺和输卵管卵）随着成熟显着增加。子房氮稳定同位素（δ15N）随成熟显着增加，但成熟阶段的增加不等于典型的每营养级3‰左右的富集。同位素生态位宽度随着成熟度呈增加趋势，同位素生态位空间在高级成熟阶段表现出更大的重叠。卵巢中 16:0、20:5n3 和 20:4n6 的相对量，追踪食肉动物和顶级捕食者，在成熟开始后增加。卵巢的整体脂肪酸谱在成熟阶段之间显示出显着差异，但在成熟鱿鱼中发现了明显的重叠。混合效应模型结果显示生殖能量与δ15N值呈正相关。繁殖能量也与 18:0 和 20:4n6 的相对量呈正相关，分别追踪食草动物和顶级捕食者。我们的结果证实，一旦成熟开始，随着能量需求的增加，鱿鱼会转而以更高营养的猎物为食进行繁殖。然而，鱿鱼并没有改变营养级的摄食习惯，而是扩大了猎物范围，同时增加了更高营养级猎物的摄入量，以满足繁殖所需的能量需求。鱿鱼可以选择这种能量获取策略，通过平衡觅食的能量摄入和消耗来最大限度地提高繁殖成功率，这需要未来的研究来阐明这种半产物种的繁殖策略。分别追踪食草动物和顶级捕食者。我们的结果证实，一旦成熟开始，随着能量需求的增加，鱿鱼会转而以更高营养的猎物为食进行繁殖。然而，鱿鱼并没有改变营养级的摄食习惯，而是扩大了猎物范围，同时增加了更高营养级猎物的摄入量，以满足繁殖所需的能量需求。鱿鱼可以选择这种能量获取策略，通过平衡觅食的能量摄入和消耗来最大限度地提高繁殖成功率，这需要未来的研究来阐明这种半产物种的繁殖策略。分别追踪食草动物和顶级捕食者。我们的结果证实，一旦成熟开始，随着能量需求的增加，鱿鱼会转而以更高营养的猎物为食进行繁殖。然而，鱿鱼并没有改变营养级的摄食习惯，而是扩大了猎物范围，同时增加了更高营养级猎物的摄入量，以满足繁殖所需的能量需求。鱿鱼可以选择这种能量获取策略，通过平衡觅食的能量摄入和消耗来最大限度地提高繁殖成功率，这需要未来的研究来阐明这种半产物种的繁殖策略。鱿鱼不会改变营养级的摄食习惯，而是扩大猎物范围，同时增加更高营养级猎物的摄入量，以满足繁殖的能量需求。鱿鱼可以选择这种能量获取策略，通过平衡觅食的能量摄入和消耗来最大限度地提高繁殖成功率，这需要未来的研究来阐明这种半产物种的繁殖策略。鱿鱼不会改变营养级的摄食习惯，而是扩大猎物范围，同时增加更高营养级猎物的摄入量，以满足繁殖的能量需求。鱿鱼可以选择这种能量获取策略，通过平衡觅食的能量摄入和消耗来最大限度地提高繁殖成功率，这需要未来的研究来阐明这种半产物种的繁殖策略。