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

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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.