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Animals exhibit seasonal cycles in a variety of physiological and behavioral traits. Studies of these cycles can potentially offer new insights into the evolution of individual differences. For natural selection to act, a trait must be both distinctive within individuals and variable among individuals. The extent to which the amplitude and phase of seasonal cycles fulfill these requirements is not well documented. As a preliminary analysis, we investigated seasonal cycles in the body mass of pigeons, which we weighed quarterly over a period of six years. [Our work with these animals complied with all applicable institutional regulations (University of Groningen Animal Experimentation Committee, license no. 5095) and Dutch and European laws.] We employed several of statistical techniques aimed at 1) quantifying the repeatability of seasonality and 2) comparing within- and among-individual variation in seasonality. Our goal is to take what we have learned from our analyses of mass and apply it to other seasonally variable physiological traits, including variables related to immune function.
This preprint submission to PeerJ was first presented as a poster at Evolution 2014 in Raleigh, NC, USA.