Specialist and generalist herbivores exert opposing selection on a chemical defense.

摘要: Summary • Plant defense traits often show high levels of genetic variation, despite clear impacts on plant fitness. This variation may be partly maintained by trade-offs in the against multiple herbivore species, for example between generalists and coevolved specialists. Despite a long-standing discussion literature subject, no study to date has specifically manipulated specialist generalist herbivores independently one another determine whether two guilds exert opposing selection pressures specific defensive traits. In separate experiments, dominant Brassica nigra were test composition community altered direction major trait plant, sinigrin concentration. It was found that damage negatively correlated but loads positively with increasing concentrations; concentration favored when specialists removed, disfavored (past an intermediate point) removed selectively neutral plants faced both These results suggest can chemical defenses, thus changes alter net selective value