Research Relative embryo length as an adaptation to habitat and life cycle in Apiaceae Filip Vandelook1, Steven B. Janssens2 and Robin J. Probert3 1Plant Ecology, Philipps-Universita¨t Marburg, Karl-von-Frisch-Strasse 8, D-35043 Marburg, Germany; 2Laboratory of Plant Systematics, Institute of Botany and Microbiology, KU Leuven, PO Box 2437, BE-3001 Leuven, Belgium; 3Seed Conservation Department, Royal Botanic Gardens Kew, Wakehurst Place, Ardingly, West Sussex RH17 6TN, UK Summary Author for correspondence: • The factors driving the evolution of the relative embryo length in Apiaceae were examined. Filip Vandelook We tested the hypothesis that seeds with large relative embryo length, because of more rapid Tel: +49 6421 2822053 germination, are beneficial in dry and open habitats and for short-lived species. We also ana- Email: fi
[email protected] lyzed to what extent delayed germination as a result of embryo growth can be considered a Received: 13 March 2012 dormancy mechanism. Accepted: 5 April 2012 • Hypotheses were tested by correlating the relative embryo length with other plant traits, habitat and climatic variables. The adaptive nature of the relative embryo length was deter- New Phytologist (2012) mined by comparing the performance of a pure drift, Brownian motion (BM) model of trait doi: 10.1111/j.1469-8137.2012.04172.x evolution with that of a selection–inertia, Ornstein–Uhlenbeck (OU) model. • A positive correlation of the relative embryo length with germination speed and negative correlations with the amount of habitat shade, longevity and precipitation were found. An Key words: Apiaceae, comparative method, dormancy, embryo, evolution, seed size.