Ontogenetic consistency in oak defence syndromes

1. Plant species allocate resources to multiple defensive traits simultaneously, which often leads to so-called defence syndromes, i.e. suites of traits that are co-expressed. While reports of ontogenetic variation in plant defences are commonplace, no research to date has tested for ontogenetic shifts in defence syndromes. In addition, we still know little about how ecological and evolutionary factors concurrently shape plant defence syndromes via ontogeny. 2. We tested for ontogenetic variation in plant defence syndromes by measuring a suite of defensive and nutritional traits on saplings and adult trees of 29 oak (Quercus, Fagaceae) species distributed across Europe, North America, and Asia. In addition, we investigated if these syndromes exhibited a phylogenetic signal to elucidate their macro-evolutionary nature, whether they were associated with levels of herbivore pressure and climatic conditions, and if such evolutionary and ecological patterns were contingent on ontogeny. ...