Oregon Cooperative Fish and Wildlife Research Unit, Department of Fisheries and Wildlife, Oregon State University, Corvallis, OR, USA.
Coastal Research and Extension Center, Mississippi State University, Biloxi, MS, USA.
J Anim Ecol. 2021 Apr;90(4):931-942. doi: 10.1111/1365-2656.13422. Epub 2021 Feb 1.
Age-related variation in reproductive performance in long-lived iteroparous vertebrate species is common, with performance being influenced by within-individual processes, such as improvement and senescence, in combination with among-individual processes, such as selective appearance and disappearance. Few studies of age-related reproductive performance have compared the role of these drivers within a metapopulation, subject to varying degrees of resource competition. We accounted for within- and among-individual changes among known-aged Adélie penguins Pygoscelis adeliae during 17 years (1997-2013), at three clustered colonies of disparate size, to understand patterns in age-related reproductive success during early and late adulthood. Age at first reproduction (AFR) was lowest, and number of breeding attempts highest, at the largest colony. Regardless of AFR, success improved with early post-recruitment experience. For both oldest and youngest recruitment groups, peak performance occurred at the end of their reproductive life span indicating a possible cost of reproduction. Intermediate recruitment groups reached peak performance in their mid-reproductive life span and with intermediate breeding experience, before decreasing. Breeding success was lowest for the initial breeding attempt regardless of AFR, but we observed subsequent variation relative to recruitment age. Gaining experience by delaying recruitment positively influenced reproductive performance early in the reproductive life span and was most evident for the youngest breeders. Oldest recruits had the highest initial and peak breeding success. Differences in AFR resulted in trade-offs in reproductive life span or timing of senescence but not in the overall number of breeding attempts. Patterns differed as a function of colony size, and thus competition for resources. Early life improvement in performance at the larger colonies was primarily due to within-individual factors and at the largest colony, AFR. Regardless of colony size late-life performance was positively related to the age at last reproduction, indicating selective disappearance of lower performing individuals. These results highlight that different life-history strategies were equally successful, indicating that individuals can overcome potential trade-offs associated with early- and late-life performance. These results have important implications for understanding the evolution of life-history strategies responsible for driving population change.
在长寿的多次生殖的脊椎动物物种中，生殖性能随年龄的变化是很常见的，其性能受到个体内部过程的影响，例如改善和衰老，同时也受到个体之间过程的影响，例如选择性的出现和消失。很少有研究比较了这些驱动因素在一个具有不同程度资源竞争的复合种群中的作用。我们在 17 年（1997-2013 年）期间，在三个大小不同的集群聚居地，对已知年龄的阿德利企鹅（Pygoscelis adeliae）进行了个体内部和个体之间的变化，以了解成年早期和晚期的年龄相关生殖成功模式。最大的聚居地的首次繁殖年龄（AFR）最低，繁殖尝试次数最多。无论 AFR 如何，早期的招募经验都会提高成功率。对于最年轻和最年长的招募群体，其最佳表现都出现在生殖寿命的末期，这表明繁殖可能有成本。中间招募群体在其生殖生命中期达到最佳表现，并具有中等繁殖经验，然后下降。无论 AFR 如何，首次繁殖尝试的繁殖成功率最低，但我们观察到相对于招募年龄的后续变化。通过延迟招募获得经验，对生殖生命早期的生殖表现产生积极影响，对最年轻的繁殖者最为明显。最年长的繁殖者的初始和峰值繁殖成功率最高。AFR 的差异导致了生殖寿命的权衡或衰老的时间，但不影响繁殖尝试的总数。由于种群大小的不同，模式也有所不同，因此存在资源竞争。在较大的聚居地，早期生活表现的改善主要是由于个体内部因素，而在最大的聚居地，是 AFR。无论种群大小如何，后期的表现都与最后一次繁殖的年龄呈正相关，这表明表现较差的个体选择性地消失了。这些结果强调了不同的生活史策略同样成功，表明个体可以克服与生命早期和晚期表现相关的潜在权衡。这些结果对于理解导致种群变化的生活史策略的演变具有重要意义。
