Ontogenetic changes in anti-herbivore defences are common and result from variation in resource availability and herbivore damage throughout plant development. However, little is known about the simultaneous changes of multiple defences across the entire development of plants, and how such changes affect plant damage in the field.
Ochoa-López et al. examine how defensive traits of Turnera velutina simultaneously change across major transitions of plant development and find that ontogenetic trajectories in physical, chemical and biotic resistance are significantly different and in several cases show opposite patterns. The results suggest that defensive trajectories are a mixed result of predictions by the Optimal Defence Theory and the Growth–Differentiation Balance Hypothesis, and emphasize the importance of incorporating multiple defences and plant ontogeny into studies of plant defence evolution.