Reproduction is a costly endeavor, and most large, long-lived, and iteroparous mammals exhibit conservative life-history tactics wherein an individual may forego or abandon a reproduction event for the sake of survival. Nevertheless, risks and benefits associated with reproduction are not equal across males and females, nor across their life. Whereas expenditure for females is associated with rearing young (e.g., lactation), expenditure for males occurs with securing mating opportunities. Young males may be more successful when dominant males are lacking, but it is less clear whether—and at what cost—young males will expend effort when those opportunities arise. We designed an experiment to quantify reproductive effort (e.g., food intake, somatic loss [body mass and fat]) of male white-tailed deer (Odocoileus virginianus) to better understand the reproductive ecology of male ungulates, with an emphasis on determining how adult males (≥4.5-years old) affect timing and extent of reproductive effort expended by yearling males (1.5-years old). Food intake, hormone levels, body mass, and somatic loss during rut were similar between yearling males that interacted with adult males and those that did not. Somatic loss by all males was greatest during peak estrus of females, but forage intake relative to metabolic body mass for yearling males was nearly twice that of adult males. Testosterone levels were lower for yearling than adult males early in rut and were related negatively to forage intake. Whereas adult males lost 20% (23.5 kg) of body mass and 31% (5.3 percentage points [ppt]) of body fat during the rut, yearling males lost 12% (9.3 kg) of body mass and 22% (4.7 ppt) of body fat. Reproductive effort by young males was not influenced by the presence of adult males, though young males expended less reproductive effort than adults. Instead, reproductive allocation occurred in a state-dependent manner, where pre-season levels of somatic reserves dictated reproductive effort, regardless of age. Like female ungulates, male deer displayed risk-sensitive reproductive allocation wherein current reproductive allocation occurred as a function of resources garnered during the prior season and were expended in a way that should have avoided over-investing and creating a tradeoff between reproduction and survival.

中文翻译：

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手中的一个值两个布什？年轻男性的生殖努力不受成年男性存在的影响

繁殖是一项代价高昂的努力，而且大多数大型、长寿和反复生育的哺乳动物都表现出保守的生活史策略，其中一个人可能会为了生存而放弃或放弃繁殖事件。然而，与生殖相关的风险和收益在男性和女性之间以及在他们的一生中都是不平等的。雌性的支出与抚养幼崽（例如哺乳期）有关，而雄性的支出则与确保交配机会有关。当缺乏优势雄性时，年轻雄性可能会更成功，但尚不清楚当这些机会出现时，年轻雄性是否会——以及以何种代价——付出努力。我们设计了一个实验来量化生殖努力（例如，食物摄入量、体细胞损失 [体重和脂肪]) 雄性白尾鹿 (Odocoileus virginianus) 以更好地了解雄性有蹄类动物的生殖生态，重点是确定成年雄性（≥4.5 岁）如何影响生殖的时间和程度一岁雄性（1.5 岁）付出的努力。与成年雄性相互作用的一岁雄性和未与成年雄性相互作用的一岁雄性在发情期间的食物摄入量、激素水平、体重和体细胞损失相似。在雌性发情高峰期，所有雄性的体细胞损失最大，但一岁雄性相对于代谢体重的饲料摄入量几乎是成年雄性的两倍。在发情早期，一岁公鸡的睾酮水平低于成年公鸡，并且与饲料摄入量呈负相关。而成年男性体重减轻了 20% (23.5 kg) 和 31% (5. 3 个百分点 [ppt]) 的身体脂肪在发情期间，一岁雄性失去了 12% (9.3 kg) 的体重和 22% (4.7 ppt) 的身体脂肪。年轻男性的生殖努力不受成年男性存在的影响，尽管年轻男性的生殖努力比成年人少。相反，生殖分配以状态依赖的方式发生，无论年龄大小，体细胞储备的季节前水平决定了生殖努力。与雌性有蹄类动物一样，雄鹿表现出对风险敏感的繁殖分配，其中当前的繁殖分配是根据前一季节获得的资源而发生的，并且以一种本应避免过度投资和在繁殖与生存之间进行权衡的方式进行消耗。7 ppt) 的体脂。年轻男性的生殖努力不受成年男性存在的影响，尽管年轻男性的生殖努力比成年人少。相反，生殖分配以状态依赖的方式发生，无论年龄大小，体细胞储备的季节前水平决定了生殖努力。与雌性有蹄类动物一样，雄鹿表现出对风险敏感的繁殖分配，其中当前的繁殖分配是根据前一季节获得的资源而发生的，并且以一种本应避免过度投资和在繁殖与生存之间进行权衡的方式进行消耗。7 ppt) 的体脂。年轻男性的生殖努力不受成年男性存在的影响，尽管年轻男性的生殖努力比成年人少。相反，生殖分配以状态依赖的方式发生，无论年龄大小，体细胞储备的季节前水平决定了生殖努力。与雌性有蹄类动物一样，雄鹿表现出对风险敏感的繁殖分配，其中当前的繁殖分配是根据前一季节获得的资源而发生的，并且以一种本应避免过度投资和在繁殖与生存之间进行权衡的方式进行消耗。生殖分配以状态依赖的方式发生，无论年龄大小，体细胞储备的季节前水平决定了生殖努力。与雌性有蹄类动物一样，雄鹿表现出对风险敏感的繁殖分配，其中当前的繁殖分配是根据前一季节获得的资源而发生的，并且以一种本应避免过度投资和在繁殖与生存之间进行权衡的方式进行消耗。生殖分配以状态依赖的方式发生，无论年龄大小，体细胞储备的季节前水平决定了生殖努力。与雌性有蹄类动物一样，雄鹿表现出对风险敏感的繁殖分配，其中当前的繁殖分配是根据前一季节获得的资源而发生的，并且以一种本应避免过度投资和在繁殖与生存之间进行权衡的方式进行消耗。