后代数量、大小和生存:长寿资本繁殖者产仔数的状态依赖优化

IF 2.9 3区 环境科学与生态学 Q2 ECOLOGY
Ecosphere Pub Date : 2025-08-12 DOI:10.1002/ecs2.70370
Marwan Naciri, Jon Aars, Magnus Andersen, Marie-Anne Blanchet, Andrew E. Derocher, Marlène Gamelon, Øystein Wiig, Sarah Cubaynes
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引用次数: 0

摘要

75年前,拉克提出,一个种群中所有个体都应该有一个最优的窝数,这是自然选择所青睐的,它能最大限度地增加招募后代的数量。虽然一些研究支持这种“共同最优”假设,但其他研究表明,最优的产蛋数量取决于母亲的状态(例如,年龄和身体状况,“状态依赖优化”)。这些对比结果表明,国家依赖程度本身可能取决于生态环境(例如,资本与收入育种)。此外,几乎所有这些研究都是在快速生活的物种上进行的,并且忽略了诸如母亲年龄和条件等变量之间的相互依赖性。在这里,我们测试了雌性是否共享一个共同的最佳产仔数,或者在一个慢节奏的资本繁殖者,北极熊(Ursus maritimus)中有一个状态依赖的最佳产仔数。为此,我们评估了(1)母亲状态对产仔数的影响,(2)母亲状态和产仔数对幼崽质量的影响,以及(3)母亲状态、产仔数和产仔数对幼崽存活率的影响,使用通径分析来解释变量之间的相互依赖关系,并使用捕获-再捕获模型来估计幼崽存活率。我们使用了34年(1992-2025)挪威斯瓦尔巴群岛地区北极熊亚群的个体数据。根据状态依赖优化假说,产仔数随母鼠年龄和体型的变化而变化。中年女性生双胞胎的可能性最高。年老和体型大的雌性通常有三胞胎。幼崽质量随着产仔数的增加而减少,而产仔数的增加意味着产仔数多的雌性分配了更多的资源用于繁殖。幼崽的质量反过来又强烈地预测了幼崽的存活率,这表明后代的存活率与后代的数量是相互交易的。在中老年母熊中,根据状态依赖优化假说,产仔率(第一年存活的幼崽数量)随着产仔数的增加而增加。总的来说,我们的结果与这种大型、慢速哺乳动物产仔少的状态依赖优化是一致的。产仔数的状态依赖性可能在资本繁殖者中更有可能出现,因为可用于繁殖的能量量是事先已知的。
本文章由计算机程序翻译,如有差异,请以英文原文为准。

Offspring number, size, and survival: State-dependent optimization of litter size in a long-lived capital breeder

Offspring number, size, and survival: State-dependent optimization of litter size in a long-lived capital breeder

Offspring number, size, and survival: State-dependent optimization of litter size in a long-lived capital breeder

Offspring number, size, and survival: State-dependent optimization of litter size in a long-lived capital breeder

Offspring number, size, and survival: State-dependent optimization of litter size in a long-lived capital breeder

Offspring number, size, and survival: State-dependent optimization of litter size in a long-lived capital breeder

Seventy-five years ago, Lack proposed that there should be an optimal clutch size shared by all individuals in a population and favored by natural selection, which maximizes the number of recruited offspring. While some studies support this “common optimum” hypothesis, others have shown that the optimal clutch size depends on maternal state (e.g., age and body condition, “state-dependent optimization”). These contrasting results suggest that the degree of state dependency might itself depend on the ecological context (e.g., capital vs. income breeding). Furthermore, almost all these studies were conducted on fast-living species and have ignored interdependencies among variables such as maternal age and condition. Here, we test whether females share a common optimal litter size or have a state-dependent optimal litter size in a slow-paced capital breeder, the polar bear (Ursus maritimus). To do so, we assess the influences of (1) maternal state on litter size, (2) maternal state and litter size on cub mass, and (3) maternal state, litter size, and cub mass on cub survival, using path analysis to account for interdependencies among variables and capture–recapture modeling to estimate cub survival. We use 34 years (1992–2025) of individual-based data from a polar bear subpopulation in the Svalbard region of Norway. In accordance with the state-dependent optimization hypothesis, litter size varied with maternal age and size. Middle-aged and sized females had the highest probability of having twins. Old and large females more often had triplet litters. Cub mass decreased with increasing litter size, whereas litter mass increased, meaning females with a large litter allocated more resources to reproduction. Cub mass in turn strongly predicted cub survival, indicating that offspring survival was traded against offspring number. In middle-aged and old females, productivity—the number of cubs surviving their first year—increased with litter size, in accordance with the state-dependent optimization hypothesis. Overall, our results are consistent with a state-dependent optimization of litter size in this large, slow-paced mammal producing small litters. State dependence of litter size may be more likely in capital breeders as the amount of energy available for reproduction is known in advance.

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来源期刊
Ecosphere
Ecosphere ECOLOGY-
CiteScore
4.70
自引率
3.70%
发文量
378
审稿时长
15 weeks
期刊介绍: The scope of Ecosphere is as broad as the science of ecology itself. The journal welcomes submissions from all sub-disciplines of ecological science, as well as interdisciplinary studies relating to ecology. The journal''s goal is to provide a rapid-publication, online-only, open-access alternative to ESA''s other journals, while maintaining the rigorous standards of peer review for which ESA publications are renowned.
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