Fitness differences and persistent founder effects determine the clonal composition during population build-up in Daphnia

During the initial stages of population build-up in new habitats, the time at which immigrants arrive may infl uence their contribution to the population and thus determine population genetic structure. While the numerical advantage associated with founder eff ects may promote dominance of the off spring of early colonizers, fi tness diff erences associated with ecological diff erences among genotypes may potentially overwhelm these founder eff ects. We conducted an outdoor mesocosm experiment to test whether the sequence of arrival determines the relative contribution of genetic lineages (clones) to populations of the water fl ea Daphnia . A set of D. galeata clones was inoculated pairwise…