Wiebe Karen L
Department of Biology, University of Saskatchewan, 112 Science Place, Saskatoon, SK, S7N 5E2, Canada.
Oecologia. 2018 Dec;188(4):1095-1104. doi: 10.1007/s00442-018-4286-0. Epub 2018 Oct 27.
Age-related improvement in reproductive performance is widespread in vertebrates and constraints at young ages are a common cause. The sex that invests energetically more in reproduction, typically the female, is predicted to show stronger age-related performance but the effect of the male's age on reproduction has often been ignored. I studied age-related reproduction of both sexes in northern flickers, in which males invest more parental care than females, predicting that the effect of age would be stronger in males than in females. Longitudinal data on individuals collected during an 18-year field study confirmed this prediction. Laying dates for females improved only between the first 2 years of her life and no other reproductive parameter changed over her lifetime when the male's age was statistically controlled. In contrast, males improved up to age five for laying date, clutch size, hatching success and fledging success. Partner familiarity (fidelity) was further associated with earlier laying, larger clutches, improved fledging success and more fledglings. There was significant assortative pairing by age but there is apparently little benefit for males to choose older females, but a benefit to females with older males. Females appear to strategically lay larger clutches when paired to old males which invest more in paternal care than younger males. This is the first example of clutch size being influenced by only male age and not female age in any bird and suggests that sex roles in parental care are important determinants of aging patterns in vertebrates with diverse life histories.
与年龄相关的繁殖性能改善在脊椎动物中很普遍，幼年时期的限制是一个常见原因。通常在繁殖中投入更多精力的性别，一般是雌性，预计会表现出更强的与年龄相关的性能，但雄性年龄对繁殖的影响常常被忽视。我研究了北美扑动䴕两性与年龄相关的繁殖情况，在这种鸟类中，雄性投入的亲代抚育比雌性更多，预计年龄对雄性繁殖的影响会比雌性更强。在一项为期18年的野外研究中收集的关于个体的纵向数据证实了这一预测。当对雄性年龄进行统计控制时，雌性的产卵日期仅在其生命的前两年有所改善，并且在其一生中没有其他繁殖参数发生变化。相比之下，雄性在产卵日期、窝卵数、孵化成功率和出飞成功率方面，直到五岁都在改善。伴侣熟悉度（忠诚度）还与更早产卵、更大的窝卵数、更高的出飞成功率以及更多的出飞雏鸟相关。存在明显的按年龄选择性配对，但显然雄性选择年龄较大的雌性几乎没有好处，而雌性与年龄较大的雄性配对则有好处。当与在亲代抚育方面比年轻雄性投入更多的老年雄性配对时，雌性似乎会策略性地产下更大的窝卵数。这是在任何鸟类中窝卵数仅受雄性年龄而非雌性年龄影响的首个例子，表明亲代抚育中的性别角色是具有不同生活史的脊椎动物衰老模式的重要决定因素。
