Costs of Incubation: Linking Incubation-Induced Alterations in Phenotype to Changes in Fitness

Auburn University, Auburn AL

Investigators

Abstract

Incubation of eggs is a critical part of reproduction in birds. Optimal growth and development of embryos takes place within a narrow range of incubation temperatures, and parents must balance the competing demands of maintaining good body condition while caring for developing eggs. The importance of incubation has often been overlooked in studies of avian reproductive costs, but incubation costs can limit both current and future reproductive success. Time and energy demands can be especially important in species where only one sex incubates. Reduced attendance by incubating parents makes it more likely that egg temperatures will deviate from that needed for optimal development. Low egg temperatures can slow development and lead to longer incubation periods, which results in greater predation risk and potentially influences the amount of energy used by developing embryos and ultimately neonate phenotype. This research with wood ducks will have 3 main components. First, previous experimental work has shown that incubation temperature influenced both incubation period and neonate phenotype of wood ducks. This project will use incubation temperature to manipulate phenotypes of neonates and then return day-old ducklings to foster mothers to raise. Effects of these temperature-induced changes to duckling phenotype on growth and development, survival, recruitment to the breeding population, and subsequent reproductive success will be examined. Second, effects of incubation temperature on metabolic rates and total energy expended by wood duck embryos will be estimated. Later, ability of ducklings incubated at different temperatures to thermoregulate and the energetic costs of thermoregulation also will be examined. Third, incubation costs of adults will be manipulated and effects of these manipulated costs on body mass dynamics, incubation behavior, within- and between-season reproductive performance, and survival of females will be examined. The project will use a life history framework to examine fitness consequences of maternal reproductive decisions. Results should re-invigorate studies of incubation patterns and their functional consequences in birds, and make new contributions to our understanding of the evolution of vertebrate life history strategies. Integration of research and education will be an important goal of the project. This will be accomplished by (1) incorporating new research findings in undergraduate and graduate courses, (2) recruiting undergraduate and graduate students to work on the project, (3) hosting a workshop for NSF-sponsored undergraduates at the Savannah River Ecology Laboratory to demonstrate field research and data management methods, and (4) integrating a K-12 activity on waterfowl reproduction, conservation and education with the Virginia Tech's Science Outreach Program (SOuP) which brings science research to broader audiences, especially K-12 teachers and students.