I eat what my mother eats. Maternal effects on food preferences in invasive amphipods

Invasive alien species achieve their success through a set of traits that give them a fitness advantage over other species. Many of them are characterised by a generalist diet with an inclination to carnivory. The feeding habits of aquatic animals depend on environmental conditions operating at the population level, but the population origin and genetic background are rarely taken into account. Therefore, this study aimed to investigate the effect of the intraspecific genetic variability on the inheritance of feeding habits. We bred individuals of an invasive amphipod, Dikerogammarus villosus (Sowinsky, 1894), under semi-natural conditions in a mesocosm system, interbreeding genetically differentiated invasive populations originating from geographically isolated areas (Danube and Dnieper Deltas) or by inbreeding within the populations. We then tested food preferences of the F1 offspring (n = 256) in a 24-hour experiment providing them three food types: leaves, fish tissue and live chironomid larvae. Our results show that, despite similar breeding conditions applied to all experimental groups, populations of different origins varied in their food preferences. It appeared that the level of necrophagy or predation depended on the origin of the maternal population. Interestingly, inter-population hybrids exhibited a higher predation rate compared to pure strains. Our research shows that some traits related to invasiveness are influenced by the maternal effects and are shaped not only by the environment, but also depend on the population origin. To better predict the course and consequences of invasions, we stress the need to study the biology of invasive species using multiple populations.