Costs, consequences and context-dependency of intrafamilial conflict

一个人在成长和发展过程中所经历的环境对该人成年后的未来健康和健康有着深远的影响。在提供父母照顾的物种中，后代通常是在一起孵化的，所以亲密的关系往往提供了生长和发育发生的社会环境。然而，由于父母的照顾对父母来说是昂贵的(在时间和精力上)，而且对幼儿生长和发育至关重要的环境资源的可获得性不可预测地变化，子女对食物和其他资源的需求往往超过父母的供应。因此，家庭成员之间可能在提供这些父母资源(父母投资；PI)方面存在利益冲突，这影响到个别子女可获得的资源数量。这种家庭内部冲突的后果可能是无处不在的，并对生活史特征和行为的多样性和进化产生重要影响，如生长率、产卵量、性吸引力和乞讨行为。个体后代可获得的资源数量取决于冲突的数量，而冲突的数量取决于家庭成员的亲属关系和环境中关键资源的可获得性。然而，尽管人们日益认识到家庭内部冲突对成长、发展和健康的重要性，但人们对构成这种冲突的机制，或资源可获得性、对这些资源的冲突以及决定冲突代价和后果的机制之间的相互关系知之甚少。作者之前对斑马雀的研究表明，尽管获得的食物较少，但在家庭冲突程度较高的情况下抚养的后代比在冲突程度较低的情况下抚养的兄弟姐妹成长得更快。因此，这些后代成年后吸引力下降，这表明快速成长和家庭冲突带来了巨大的代价。这些成本很可能是氧化应激增加的结果，氧化应激是正常代谢过程的副产品--高水平的自由基--对各种细胞成分造成损害时发生的。抗氧化剂提供保护，防止自由基的破坏性影响。总抗氧化防御的一个重要组成部分是由脂溶抗氧化剂提供的，如从饮食中提取的类胡萝卜素和维生素E。抗氧化剂的饮食可获得性与家庭内部冲突之间的相互作用以前没有被考虑过，但很可能是重要的，因为抗氧化剂可获得性的变化决定了自我维持与生长和生殖投资之间的权衡，从而决定了健康。该项目计划利用人工饲养和双亲移出实验以及交叉培养来梳理性别冲突和兄弟姐妹竞争对后代生长和健康的影响，通过测量氧化应激和控制饮食抗氧化剂的可获得性来检查生长的成本基础，并建立与其运行的社会和环境背景相关的行为机制。这项工作将营养、生殖生态生理学和环境不确定性与行为生态学结合起来，研究生命早期社会和环境影响的变化对成年人健康和健康的影响的成本和后果。如果获得资金，该项目将在格拉斯哥大学生物和生命科学研究所进行，使用斑马雀作为模式物种。

The environment that an individual experiences during growth and development has profound implications for the future health and fitness of that individual during adulthood. In species that provide parental care offspring are usually reared together in broods, so close relations often provide the social environment in which growth and development takes place. However, because parental care is costly to parents (in time and energy), and availability of environmental resources essential for growth and development of young varies unpredictably, offspring demand for food and other resources often exceeds parental supply. As a consequence there may be conflicts of interest among family members over the supply of these parental resources (parental investment; PI), which affects the amount of resources available to individual offspring. The consequences of such conflicts within families can be pervasive, and have important effects for the diversity and evolution of life-history traits and behaviours such as growth rates, clutch size, sexual attractiveness and begging behaviour. The amount of resources available to individual offspring depends upon the amount of conflict, which is determined by the relatedness of family members and the availability of key resources in the environment. However, although the importance of within-family conflicts for growth, development and fitness is increasingly being recognised, very little is known about the mechanisms that underpin such conflicts, or the interrelationships between resource availability, conflict over these resources and the mechanisms that determine the costs and consequences of conflict. Previous work on zebra finches by the author showed that, although receiving less food, offspring reared under conditions of higher within-family conflict had faster growth compared to siblings reared under lower levels of conflict. As a result these offspring were less attractive as adults, indicating a substantial costs of rapid growth and of family conflict. These costs are most probably a consequence of increased oxidative stress, which occurs when high levels of free radicals, which are by-products of normal metabolic processes, cause damage to various cell components. Antioxidants provide protection against the damaging effects of free radicals. An important component of total antioxidant defence is provided by fat-soluble antioxidants, such as carotenoids and vitamin E, which are derived from the diet. The interaction between dietary availability of antioxidants and within-family conflicts has not previously been considered, but is likely to be important as variation in antioxidant availability determines the trade-off between self-maintenance and investment in growth and reproduction, and hence fitness. This project plans to use brood size manipulations, hand-rearing and parent removal experiments and cross-fostering to tease apart the effects of sexual conflict and sibling competition on growth and fitness of offspring, examine the cost basis of growth through the measurement of oxidative stress and manipulation of dietary antioxidant availability, and establish the behavioural mechanisms that underlie the allocation of PI in relation to the social and environmental context in which they are operating. The work integrates nutrition, reproductive ecophysiology and environmental uncertainty with behavioural ecology in examining the costs and consequences of variation in social and environmental effects early in life on adult health and fitness. If funded, the project would be conducted at the Institute of Biological and Life Sciences at the University of Glasgow, using zebra finches Taeniopygia guttata as a model species.