The role of ontogeny in wood diversity and evolution.

Evolutionary developmental biology (evo-devo) explores the link between developmental patterning and phenotypic change through evolutionary time. In this review, we highlight the scientific advancements in understanding xylem evolution afforded by the evo-devo approach, opportunities for further engagement, and future research directions for the field. We review evidence that (1) heterochrony-the change in rate and timing of developmental events, (2) homeosis-the ontogenetic replacement of features, (3) heterometry-the change in quantity of a feature, (4) exaptation-the co-opting and repurposing of an ancestral feature, (5) the interplay between developmental and capacity constraints, and (6) novelty-the emergence of a novel feature, have all contributed to generating the diversity of woods. We present opportunities for future research engagement, which combine wood ontogeny within the context of robust phylogenetic hypotheses, and molecular biology.