Reproductive performance of a tropical apex predator in an unpredictable habitat
Reproductive performance of a tropical apex predator in an unpredictable habitat
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DOI：
10.1007/s00265-018-2521-7
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发表时间：
2018-07-01
影响因子：
2.3
通讯作者：
Krueger, Oliver
中科院分区：
文献类型：
--
作者：
Kalberer, Stephanie;Meise, Kristine;Krueger, Oliver
生活史特征的变化与个体的健康状况直接相关。这种相互作用因不可预测的栖息地中的环境扰动而变得复杂。为了最大限度地适应环境，个体通过在维持、生长和繁殖之间重新分配资源来应对环境变化。分离这些因素是复杂的，因为特征是通过当前繁殖与未来生存和繁殖之间的权衡而相互联系的。这项研究首次估计了热带顶端捕食者加拉帕戈斯海狮(Zalophus Wollebaeki)在不可预测的栖息地加拉帕戈斯群岛的生活史特征和权衡。13年来关于出生质量、早期生长和后代的个人数据，以及环境数据，使人们能够检查影响成年雌性生殖性能的因素，并计算幼崽比率。雌性在4岁至9岁之间开始初产。雌性出生第一年的海洋和身体状况都不会影响初产时的年龄。初产时的年龄对雌性的出生率没有影响，平均每两年就有一只幼崽。幼崽的性别不会影响随后的出生间隔，但一岁幼崽的存活率延长了这一间隔。在6岁之前，女性的出生率较低(<；0.40)。6~14岁生育力较高(出生率0.40~0.48)。我们没有发现年际不同的海洋条件对幼体增长率的影响。雌性加拉帕戈斯海狮似乎通过低但稳定的繁殖产量来应对早期生活史特征的变化和环境的不可预测性，只有在当前和未来繁殖之间的权衡才能修正。在温带地区和季节性但可预测的热带生境中，许多物种的生活史特征和权衡已被研究过。然而，在热带但不可预测的生境中，很少对长寿物种进行研究，在那里，生活史特征、个体健康状况和种群人口统计学之间的相互作用可能更加复杂。我们对热带顶端捕食者加拉帕戈斯海狮雌性海狮的长期数据集表明，当前和未来繁殖之间的权衡在它们的生活史上占有重要地位。然而，它们产生了低但稳定的生殖产量，在很大程度上不受早期生活史特征变化的影响，也在很大程度上与环境的不可预测性无关。
Variation in life history traits is directly linked to individual fitness. This interplay is complicated by environmental perturbations in an unpredictable habitat. To maximise fitness, individuals react to environmental changes by reallocating resources between maintenance, growth and reproduction. Disentangling these factors is complicated as traits are interlinked by trade-offs between current reproduction and future survival and reproduction. This study provides first estimates of life history traits and trade-offs of a tropical apex predator, the Galapagos sea lion (Zalophus wollebaeki), in an unpredictable habitat, the Galapagos archipelago. Thirteen years of individual data on birth mass, early growth and offspring, and environmental data allowed the examination of factors influencing reproductive performance of adult females and calculation of pupping rates. Females became primiparous between ages 4 and 9. Neither oceanographic nor body condition in the females' first year of life influenced age at primiparity. Age at primiparity had no effect on a female's birth rate, on average one pup every 2 years. Sex of a pup did not influence the subsequent inter-birth interval, but first-year pup survival lengthened it. Until age 6, females showed lower birth rate (< 0.40). Fecundity was higher between age 6 and 14 (birth rate 0.40-0.48). We could not detect an influence of inter-annually differing oceanographic conditions on pupping rates. Female Galapagos sea lions appear to deal with variation in early-life history traits and environmental unpredictability by a low but stable reproductive output modified only by the trade-off between current and future reproduction.Life history traits and trade-offs have been examined in many species in temperate regions and in seasonal but predictable tropical habitats. However, they have rarely been investigated in long-lived species in tropical but unpredictable habitats, where the interplay between life history traits, individual fitness and population demography may be more complex. Our long-term dataset for Galapagos sea lion females, a tropical apex predator, shows that the trade-off between current and future reproduction figures prominently in their life history. However, they produce a low, but stable reproductive output largely unaffected by variation in early life history traits and largely independent of environmental unpredictability.