Individual variation in workload during parental care: can we detect a physiological signature of quality or cost of reproduction?
Individual variation in workload during parental care: can we detect a physiological signature of quality or cost of reproduction?
复制标题
育儿期间工作量的个体差异：我们能否检测生殖质量或成本的生理特征？
作者：
T. Williams;M. Fowler
在父母照料、雏鸟饲养或为雏鸟提供食物的过程中，鸟类的工作有多辛苦？如果鸟类确实努力工作，我们能察觉到个体在工作负荷能力(可能与“质量”有关)或与高工作负荷相关的成本方面存在差异的生理特征吗？在这里，我们就这些问题提供一个宽泛的概念性视角。生活史理论预测(或要求)：(1)父母照顾是一项艰苦的工作，(2)在父母照顾上投入更多资金的人在养育更多、更大、更健康的后代方面受益，但(3)增加对父母照顾的投资是有代价的：未来的繁殖力和/或存活率下降。然而，我们首先强调了与这种传统观点不一致的研究，例如：(1)女性通常不会为增加的工作量付出生存代价(尽管男性会)，(2)一些(高质量？)个体似乎最大限度地利用了许多生活史特征，(3)父母照料期间的工作量通常不能预测生产率。我们建议，从“运动生理学”的角度来看待父母的照料可能是有益的，但强调了这样一个事实，即现有的运动模式往往涉及与自由生活动物觅食时所经历的情况非常不同的条件(例如，使用强迫运动)，并且经常脱离自由生活动物中运动和获取资源之间的关键关系。我们简要回顾了自由生活鸟类在父母照料期间工作量对生理影响的研究，但再次强调了我们在这一领域令人惊讶的缺乏知识，特别是在工作量的实验操纵与全面的生理分析相结合的情况下。最后，我们提出了三点建议：(1)工作负荷的实验操作；(2)对大量已知个体获得更好的工作负荷测量；(3)更好地评估个体素质的生理学，以及确定工作负荷引起的“磨损”的具体指标。
How hard do birds work during parental care, chick rearing, or provisioning of their nestlings? And if birds do work hard, can we detect a physiological signature of individual variation in workload ability (perhaps related to ‘quality’) or costs associated with high workload? Here, we provide a broad conceptual perspective on these questions. Life-history theory predicts (or requires) that (1) parental care is hard work, (2) individuals that invest more in parental care benefit in terms of rearing more, larger, fitter offspring, but that (3) increased investment in parental care comes at a cost: decreased future fecundity and/or survival. However, we start by highlighting studies that are inconsistent with this conventional view, e.g., (1) females often do not pay a survival cost of increased workload (though males do), (2) some (high quality?) individuals appear to maximise numerous life-history traits, and (3) workload during parental care often does not predict productivity. We suggest that an “exercise physiology” perspective on parental care might be informative, but highlight the fact that existing models of exercise often involve conditions very different from that free-living animals experience while foraging (e.g., using forced exercise) and are often divorced from the critical relationship in free-living animals between exercise and acquisition of resources. We briefly review studies looking at physiological effects of workload during parental care in free-living birds, but again highlight our surprising lack of knowledge in this area especially where experimental manipulation of workload is coupled with comprehensive, physiological analysis. Finally, we make three recommendations for how can we advance the study of physiology of parental care in chick-rearing birds: (1) experimental manipulation of workload, (2) obtaining better measures of workload, for large numbers of known-individuals, and (3) better assessment of physiology of individual quality, and identification of specific metrics of workload-induced ‘wear and tear’.