S4.3-2 Sunday, Jan. 5 14:00 Statistical approaches to uncovering ecological and evolutionary causes and consequences of behavioral and physiological differences among individuals. DOWNS, C.J.*; DOCHTERMANN, N.A.; University of Nevada Reno; North Dakota State University email@example.com
Considerable work in ecoimmunology focuses on investigating individual variation in immune responses and linking this variation to physiological trade-offs, ecological traits, and environmental variation. Variation in immune responses, however, can be partitioned into differences between and within individuals, populations, and taxonomic groupings. Understanding how variation, and in particular how covariation across traits, is distributed among these levels is necessary for drawing appropriate ecological and evolutionary inferences. Moreover, variation at the between-individual level directly connects to underlying quantitative genetic parameters. In order to fully understand immune responses in evolutionary and ecological contexts and to reveal phylogenetic constraints on evolution, statistical approaches must allow (co)variance to be partitioned among levels of individual, population, and phylogenetic organization (e.g., population, species, genera, etc.). Here we describe how mixed-effects models allow variation in immune responses to be partitioned among different hierarchical levels. We detail the connection between these approaches and relevant ecological and evolutionary questions involving immune responses. For example, a between individual correlation (i.e., a correlation between mean responses of individuals) might pose evolutionary constraints or with-in lifetime constraints and trade-offs. We conclude by discussing the advantages of this approach when developing hypotheses about evolutionary constraints, investigating life history trade-offs, and developing predictions about ecological and evolutionary trajectories.