Data & code for - The effect of experimental hybridization on cognition and brain anatomy: limited phenotypic variation and transgression in Poeciliidae

The role of hybridization as a driver of variation and novelty in traits linked to fitness is well recognized, yet it remains largely unknown whether hybridization can fuel behavioural novelty by promoting phenotypic variation in brain morphology and/or cognitive traits. In this study, we investigated the effect of hybridization on brain anatomy, learning ability, and cognitive flexibility in first- and second-generation hybrids of two closely related fish species (<em>Poecilia reticulata</em> and <em>P. wingei</em>). <br> This depository contains a README file detailing information contained in each data file, the datasheets that identify the crossing group of each fish, the raw data from the brain morphology measurements, the raw data from the associative learning and reversal learning tasks, and a processed data table containing information on the performance of the fish in both tasks (learning criterion). We also provide the R code used for all analyses and to generate the graphs presented in the manuscript.