DISSERTATION RESEARCH: Immune-based Maternal Effects: Investigating Variation and Plasticity in Female Deposition of Protective Immune Compounds into Eggs

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One thing birds can do to protect their young from the threat of bacteria in the environment is to transfer protective immune compounds, such as antibodies, directly into their eggs. Although these antibodies are associated with improved offspring growth and immunity, it is not known how levels of egg antibodies are influenced by disease risk. The purpose of this project is to test the hypothesis that tree swallows (Tachycineta bicolor) encountering more bacteria in their nests will have higher levels of antibodies in their eggs. To tackle this question, bacterial communities in swallow nests will be characterized using DNA-sequencing and compared with antibody levels in eggs collected from the same nests. This data set, from across North America, will be the most comprehensive ever collected on bacterial communities associated with any bird species, and the investigators predict that, as in plants and animals, bacterial diversity will be highest at the most southerly sites (e.g., Virginia) and lowest at the most northerly sites (e.g., Alaska). As a consequence, southern birds should have more antibodies in their eggs than northern birds. In addition to exploring new ground in bacterial biogeography, this study will bring new perspective to the variety of ways in which female birds can protect their offspring. Results from this study will also contribute to a large collaborative study of investigators working to quantify pathogens inhabiting the nests, feathers, feces, blood, and tissues of swallows through the NSF-funded Golondrinas de las Americas network. And sequence data will add to a growing wealth of 16S rRNA gene sequences publically available through GenBank. This project will also contribute to the training of undergraduates working in the field and laboratory. Through this research, students will have the opportunity to share data, ideas, and personal interactions with investigators throughout the hemisphere.