Genetic control of feeding preference in the herbivorous amphipod Ampithoe longimana

The feeding preferences of individuals within a single species of marine consumer can differ because of variation in ontogeny, physiological state and environmental conditions; yet genetic variation can also play a central (largely undescribed) role. This study describes the nature of the genetic inheritance of feeding preference in the herbivorous amphipod Ampithoe longimana. Two populations known to have strong feeding preference for the chemically rich seaweed Dictyota menstrualis (from North Carolina, USA) were crossed to an F2 generation with 2 populations known to have lower preference for the seaweed (i.e. from Connecticut and Massachusetts), and all parental and hybrid lines were assayed for their feeding preferences. F1 hybrids of A. longimana populations with high and low D. menstrualis preference displayed preferences intermediate to both parental lines, and there were no persistent differences among sexes in the inheritance of D. menstrualis preference in the F1 or F2 generations. These results suggest that feeding preference for D. menstrualis is likely a polygenic trait inherited in a largely additive manner on autosomes. The presence of substantial polygenic control of feeding preference among this and perhaps other marine consumers suggests that the genetic potential for local adaptation of this trait may be more common than currently appreciated.