DISSERTATION RESEARCH: Environmental Quality and the Costs of Reproduction: an Experimental Test in a Cooperatively Breeding Bird

生物体面临着一个基本的决定：是将宝贵的资源和能量用于繁殖还是用于自身的生存。因此，繁殖可能导致存活率降低，这种关系被称为“繁殖成本”。对于一些生物来说，繁殖的成本被认为是如此之高，以至于父母没有额外的帮助就无法繁殖。最终，这可能就是为什么一些物种生活在复杂的家庭群体或合作繁殖社会中，在这些社会中，个体组成社会群体来抚养其他物种的后代。为幼崽寻找食物很困难，但如果个体聚集在一起寻找食物，繁殖的成本就会降低。研究人员正在研究合作繁殖的鸟类，以确定繁殖的成本是否会促进家庭群体中养育后代。该项目特别探讨了繁殖过程中可用的资源如何增加或减少繁殖成本并改变群体动态。这项研究还将为肯尼亚当地的实地助理创造两个职位，并为一名女本科生提供指导，她将协助收集数据并从事一个独立的项目。结果将与美国和肯尼亚的本科生分享，作为热带生物学海外学期的一部分。这项研究还将通过参与基层的莱基皮亚保护俱乐部，与肯尼亚农村小学的学生分享。研究人员将通过在一种合作繁殖的物种——超级椋鸟（Lamprotornis superbus）的巢穴中添加昆虫来操纵领地质量，以检查环境条件是否会导致繁殖成本的增加。在雏鸟饲养之前和饲养过程中，都会捕捉到雏鸟，以观察由于繁殖而发生的生理变化。先前对该系统的研究表明，氧化应激随着饲养小鸡的努力而增加，这是一个强有力的候选措施，可能将繁殖努力与降低存活率联系起来。研究人员将研究食物补充如何改变这些生理变化的幅度，以推断资源的可用性如何驱动繁殖成本。样本和数据将储存在哥伦比亚大学，并在出版后通过进化和生态数据的公共数据库Dryad向公众提供。

Organisms are faced with a fundamental decision: to invest valuable resources and energy in reproduction or in their own survival. As a result, reproduction may lead to lowered survival, a relationship called the "cost of reproduction." For some organisms, the cost of reproduction is thought to be so high that parents cannot reproduce without additional help. Ultimately, this may be why some species live in complex family groups, or cooperatively breeding societies, where individuals form social groups to raise others' offspring. Finding food for the young is difficult, but if individuals come together to find food the cost of reproduction is lowered. The researchers are studying cooperatively breeding birds to determine whether the cost of reproduction promotes rearing young in family groups. This project specifically explores how resources available during reproduction can increase or decrease the cost of reproduction and alter group dynamics. This research will also create two positions for local Kenyan field assistants, and provide mentoring to a female undergraduate student who will assist with data collection and pursue an independent project. Results will be shared with US and Kenyan undergraduate students as part of a semester abroad in Tropical Biology. This research will also be shared with Kenyan students from rural elementary schools through participation in the grassroots Laikipia Conservation Clubs. Researchers will manipulate territory quality through an insect supplementation at nests of a cooperatively breeding species, the superb starling (Lamprotornis superbus), to examine whether environmental conditions drive the cost of reproduction. Birds will be caught both before and during chick rearing to look at the physiological changes that occur as a result of reproduction. Previous research in this system has indicated that oxidative stress increases with greater chick-rearing effort, a strong candidate measure that may link reproductive effort to reduced survival. The researchers will examine how food supplementation alters the magnitude of these physiological changes to infer how resource availability drives the cost of reproduction. Samples and data will be stored at Columbia and made publically available post publication through Dryad, a public data repository for evolutionary and ecological data.