An Evolutionary Analysis of Biparental Care

一夫一妻制的配偶在基因上没有联系，他们有一些共同的兴趣，另一些则不一致。 在为巢栖幼仔提供昂贵的双亲照料的地方，性伙伴关系很可能是合作和自私的复杂混合体：每个个体都可以通过让伴侣提供更大的投资来提高其一生的生殖成功率。 最近的ESS模型预测，这样的父母只应该部分补偿配偶的任何不足，但应该随着自己的未来（其剩余生殖价值）的减少而变得更加慷慨。 由于许多因素影响生活史参数不对称根据性别，ESS的方法导致新的预测父母的分工。 拟对家雀进行的实地观察和实验将探讨这些动态。 人工增加提供育雏所需的亲代劳动力（通过将一个亲代略微固定在一个临时固定在腹鳍上的小铅捕鱼砝码），并记录征税亲代及其配偶的食物输送性能。 与此同时，他们的日常能量消耗将通过双标记水技术进行评估。 在其他巢穴，父母照顾的成本将被人为地降低（通过食物替代），并将确定对雄性和雌性父母的影响。 由于家雀是非常久坐和繁殖繁殖在一个季节内，它应该是可能的，以作出强有力的评估如何增加父母的努力影响未来的成年繁殖性能和当前的育雏招聘。 初步支持期的总体目标是：（1）在三个层面（行为、能量消耗和未来繁殖成功率）检查雄性和雌性父母照顾的单独成本;（2）衡量父母提供的可变水平对整个后代的影响;（3） 调整双亲照料的ESS模型，以解释在这个特定系统中观察到的男性和女性之间的差异：（4）检验当前ESS模型关于父母努力和努力的性别差异与其成本的关系的几个关键预测;以及（5）评估从一个筑巢周期到下一个筑巢周期伙伴关系的中断是否取决于每个父母的相对工作量的中断。

Being unrelated genetically, monogamous mates have some interests in common, others at odds. Where costly biparental care is provided to nidicolous young, the sexual partnership is likely to be a complex mixture of cooperation and selfishness: each individual may enhance its lifetime reproductive success by getting its partner to supply the greater investment. Recent ESS models predict that such a parent should compensate only partially for any shortfall by its mate, yet should become more generous as its own future (its residual reproductive value) diminishes. Because many factors influence life-history parameters asymmetrically according to gender, the ESS approach leads to novel predictions regarding the parental division of labor. The proposed field observations and experiments on house sparrows will explore these dynamics. Parental labor required for provisioning the brood will be artificially increased (by slightly encumbering one parent with small lead fishing weights affixed temporarily to the rectrices) and the food-delivery performances of both the taxed parent and its mate will be recorded. At the same time their daily energy expenditures will be assessed via the doubly-labelled water technique. At other nests, the costs of parental care will be artificially decreased (via food supplementations) and the impact on both male and female parents will be determined. Because house sparrows are remarkably sedentary and breed multiply within a season, it should be possible to make robust assessments of how increased parental exertion affects both future adult reproductive performance and current-brood recruitment. The overall goals of the initial support period are: (1) to examine the separate costs of male and female parental care at three levels (in terms of behavior, energy expenditure, and future reproductive success); (2) to measure the impact of variable levels of parental provisioning on whole broods of offspring; (3) to tailor ESS models of biparental care so as to account for observed differences between males and females in this particular system; (4) to test several key predictions from current ESS models about how parental effort and sex differences in effort should relate to its costs; and (5) to assess whether discontinuation of partnerships from one nesting cycle to the next is contingent on disruptions of the relative workloads of each parent.