LEAF SIZE, SAPLING ALLOMETRY, AND CORNERS RULES - PHYLOGENY AND CORRELATED EVOLUTION IN MAPLES (ACER)

We studied the evolution of leaf size, sapling canopy allometry, and r elated traits in 17 Acer species growing in the understory of temperat e deciduous forests, using parsimony methods, randomization tests, and independent contrasts calculated on a phylogeny inferred from nuclear ribosomal internal transcribed spacer (ITS) sequences. Bivariate corr elations and multivariate analyses indicated two independent suites of coevolving traits, and the results were robust over a range of altern ative phylogenies. The first suite consisted of strong positive correl ations among twig thickness, leaf size, inflorescence length, and bran ch spacing (Corner's rules). Seed size and mature height were also wea kly correlated with these traits. The second suite reflected aspects o f sapling crown allometry, including crown size, stem diameter, and to tal leaf area, which appear to be related to shade tolerance. There wa s a weak negative correlation between sapling crown size and mature he ight, but no correlation with leaf or seed size. Most correlations wer e similar in magnitude for ahistorical and independent contrasts analy ses, and discrepancies between these two measures were greater in trai ts with lower levels of convergent evolution. The evolutionary correla tions among twig, leaf, seed, inflorescence, and canopy dimensions emp hasize the need for integrated theories of evolution and function of t hese disparate traits.