DISSERTATION RESEARCH: Fitness Cost of Nest Defense: A Trade-Off With Offspring Care?

论文研究：雀形目鸟类巢防的适应性成本：与后代护理的权衡？PI：Stephen Nowicki Renee A.在许多生物中，幼仔的生长和生存能力取决于他们从父母那里得到的照顾。尽管父母的照顾对后代的生存很重要，但成年人提供的照顾的数量和质量往往差异很大。观察到这种差异的原因之一可能是因为个人在使用其时间和资源进行父母照顾和其他活动方面面临权衡。一个健身成本表达的巢防御行为最近记录在西部蓝知更鸟（Sialia mexicana）。蓝知更鸟从保护巢穴免受竞争对手的攻击中获益，因为合适的繁殖巢穴是有限的资源。然而，雄性西部蓝知更鸟更积极地保卫自己的巢穴，平均每年产生的后代更少。拟议的研究检查了三个替代假设，可以解释这种观察到的巢防御行为和繁殖成功之间的关系。具体来说，它测试是否有后代的照顾和防御之间的时间/能量权衡，是否侵略性的男性本质上是贫穷的父母，或者是否海拔和巢防御之间的相关性最好地解释了巢防御和繁殖成功之间的关系。确定父母成功抚养后代的能力产生变化的机制对于我们理解父母投资策略的演变至关重要。

DISSERTATION RESEARCH: FITNESS COST OF NEST DEFENSE IN A PASSERINE BIRD: A TRADE-OFF WITH OFFSPRING CARE?PI: Stephen Nowicki & Renee A. DuckworthIn many organisms, the ability of young to grow and survive depends on the care they receive from their parents. Despite the importance of parental care for offspring survival, adults often vary widely in the quantity and quality of care they provide. One of the reasons why this variation is observed may be because individuals face a trade-off in the use of their time and resources for parental care and for other activities. A fitness cost to the expression of nest defense behavior was recently documented in western bluebirds (Sialia mexicana). Bluebirds benefit from defending their nest cavities from competitors because suitable breeding cavities are a limited resource. However, male western bluebirds that defend their nests more aggressively produce fewer offspring on average each year. The proposed research examines three alternative hypotheses that could account for this observed relationship between nest defense behavior and reproductive success. Specifically, it tests whether there is a time/energy trade-off between offspring care and defense, whether aggressive males are inherently poorer parents, or whether a correlation between elevation and nest defense best explains the relationship between nest defense and reproductive success. Identifying the mechanisms that produce variation in parents' ability to raise young successfully is essential for our understanding of the evolution of parental investment strategies.