Classic studies of plant–insect systems often emphasize the taxonomic basis of host use by herbivores -- with many observations of herbivores being associated with narrow groups of related plant species. A prediction arising from these patterns is that the phylogenetic relatedness of hosts, and their similarity in traits, will impact the fitness of specialized herbivores. Here, we use the experimental evolution of spider mites to measure the costs associated with specializing on a novel cucumber host, in terms of fitness trade-offs on a phylogenetically-nested set of seven alternative host species.
Results/Conclusions
Our study revealed that evolution on the novel cucumber hosts resulted in a general trend of increased fitness on all seven hosts, relative to fitness of non-cucumber specialized spider mites. Further, we did not detect a negative interaction of the effects of specialization on cucumber and the phylogenetic distance of each alternative host plants. Our findings suggest that, contrary to the conventional prediction of fitness trade-offs associated with specialization, selection for host use of one plant species may positively impact herbivore fitness on alternative, yet related, host species.