The life history trade-off between immune function and brain development

As immunity has been proven to be costly in energetic terms, these investments are likely to conflict with other, important and energy-demanding fitness traits. Several studies have addressed trade-offs between the immune-system and other factors, like gr owth, development or reproductive investment and success. Here, we will test the hypothesis that the high costs associated with immune-responses will lead to a trade-off between immunity and neural development. A proper cognitive development is essentia l for the long time survival for an organism, but priority to specific immune responses is among the most important for short time survival. Thus, in sensitive periods with enhanced neural development, we expect that immune challenges will set limits for how much the organism can invest in brain development. Thus, our hypothesis is that during an infection, the immediate reduction of short-term mortality should be prioritized over investments that may reduce mortality on the longer term like neural dev elopment. To test this general hypothesis, we will with experiments on zebrafish address the following more specific hypotheses: a. Behavioural and concomitant neural development has an energetic cost. b. An immune response during a window of cognitive development reduces: b1. behavioural performance, and b2. neural development of the brain. This will be accomplished by a combination of behavioural experiments and immuno-histogical methods. Following up data gained from o ur experiments, we will further investigate how immune and neural investments may differ between the sexes, and thereby discuss these traits as important traits in sexual selection. Thus, by investigating a trade-off between immunity and brain development , we will contribute to better understanding the link between immunity and other main fitness traits.