Evolution of feeding preference in a leaf beetle: the importance of phenotypic plasticity of a host plant.

Much attention has been paid to ecology and evolution of damage-induced plant responses. Recently, it has been emphasized that phenotypic plasticity, such as induced plant responses, has the potential to lead to evolutionary changes of interacting partners. Here, we report that induced plant regrowth promotes a locally adaptive feeding preference of a leaf beetle, Plagiodera versicolora. We found that there was among-population variation in the strength of the feeding preference of the leaf beetle for leaf-age types of conspecific host plants. The strength of the preference was positively correlated to leaf production of host plants across populations, and the intensity of induced regrowth was likely to have been responsible for geographic variation in new leaf production. Within one population, we detected a significant additive genetic variance and heritability in the preference for consuming new vs. old leaves. Moreover, the strength of preference was significantly related to egg production depending on the leaf-age types. Thus, allopatric populations can evolutionarily develop different adaptive preference, according to locally distinct patterns of induced host regrowth.