Evolution of insect‐plant relationships ‐ a devil's advocate approach*

Most hypotheses concerning the evolution of insect‐plant relationships are based on the assumptions that, (1) phytophagous insects reduce plant fitness, and that (2) insect‐plant relationships are the result of unconstrained selection. It can be shown, however, that there is little evidence to support these assumptions. As an alternative, it is proposed that the evolution of insect‐plant relationships results primarily from autonomous evolutionary events; namely from heritable functional changes within the insects' nervous system that determine plant recognition and ultimately host plant specificity. These changes cannot be evoked by selective ecological agents. They originate from intrinsic changes (mutations sensu lato ) within the insect genome. Ecological factors play a secondary role: by either supporting or preventing the establishment of the new genotype with the novel food preference.