Directional selection failed to produce changes in olfactory Y-maze learning and memory but induced changes in climbing phenotypes.

Learning and memory are fundamental complex traits that allow for assessment and response to changes in their environment. Beyond cognition, these high order traits require several subcomponents, from sensory perception to motor output, in order to execute the intended response to a stimulus. Within the population, we see variation among individuals in abilities to perform learning and memory tasks. It is still largely unknown what genetic factors contribute to variability in these phenotypes; therefore, our study aims to gain better insight by utilizing a directional selection paradigm to drive differences in olfactory learning and memory behavior. Directional selection experiments allow for evaluation of the response to selective pressures across multiple biological levels through amplification of phenotype differences between groups. We used a reward based olfactory associative learning and memory assay to train a synthetic population of flies allowing only those who passed both tests to mate across ten generations. Our study shows significant changes in the climbing subcomponent required to perform well on the y-maze assay, however, we did not observe any significant changes to olfactory learning and memory behavior.