Post, John R.Mogensen, Stephanie2023-10-272023-10-272023-10-26Mogensen, S. (2023). Consequences and trade-offs of variation in growth rate in juvenile animals (Doctoral thesis, University of Calgary, Calgary, Canada). Retrieved from https://prism.ucalgary.ca.https://hdl.handle.net/1880/11747910.11575/PRISM/42322Growth is a crucial life history trait in juvenile organisms that can influence survival and adult reproductive capacity. In this thesis, I investigate how variation in growth and its trade-offs with other traits affect important life-history outcomes, both across and within species. I first used a meta-analytic approach to assess the magnitude and direction of key trade-offs (immune function, structural function, starvation resistance, and predation mortality) across animal taxa. Trade-offs are not ubiquitous and vary in both magnitude and direction. Although taxon-specific differences are apparent, for most trade-offs the lack of coverage across species constrained my assessment of taxon-specific patterns. I then assessed the extent to which intra-population variability in growth rate was coupled to behavioural and physiological differences and whether these differences were grouped into behavioural syndromes. I assessed this question using an experiment with a single strain of young-of-the-year rainbow trout (Oncorhynchus mykiss). I did not find evidence of behavioural syndromes in the assessed behavioural traits. In addition, growth rate did not vary with the measured traits during the experiment. Finally, I used an individual-based model to assess the importance of inherent growth rate for shaping end-of-growing-season distributions of growth in teleost fish, using basic assumptions about predation risk and density dependence. In and of themselves, realistic distributions of growth did not convey much benefit to faster growing fish. However, in the presence of even modest initial variation in size (particularly if that variation is correlated with growth rates) the benefits of fast growth increase. These findings have important implications for the life-history of juvenile animals.enUniversity of Calgary graduate students retain copyright ownership and moral rights for their thesis. You may use this material in any way that is permitted by the Copyright Act or through licensing that has been assigned to the document. For uses that are not allowable under copyright legislation or licensing, you are required to seek permission.Life-historyTrade-offsGrowthEcologydoctoral thesis