RESULTS
The phylogenetic signals in seed mass and leaf size were moderate and
statistically significant across palms, other monocots, dicots, and
gymnosperms (Table 1; Fig 2), indicating that seed mass and leaf size
have a common evolutionary history with species. We detected a strong
phylogenetic signal in plant height of other monocots, dicots and
gymnosperms but not palms (Table 1; Fig 2).
When controlling for phylogeny, seed mass showed significantly positive
correlation with leaf size across plant species (Table 2; Fig 3).
However, plant height was positively correlated with seed mass in other
monocots and dicots rather than palms and gymnosperms (Table 2, Fig 3).
The first two axes of the Principal Component Analysis (PCA) together
accounted for 87.3% of variability in the functional traits of plant
species (P < 0.001, R2 = 0.154,
permutations = 999). The principal axis (PC1) was determined positively
by seed mass and plant height. The second axis was significantly and
positively correlated with leaf area (Fig 4). Thus, dicots were
ordinated in a triangle of multivariate space, while palms, gymnosperms
and other monocots were ordinated in three separated spaces, with
large-seeded palms at the positive extreme of PC1 and small-leaved
gymnosperms at the negative extreme of PC2 (Fig 4).
The partial R2 for the logistic regression model
showed that leaf size and phylogeny explained the vast majority of
variation in seed mass across palm species (partial
R2lik = 15.79%, ΔlogLik = 13.7, P <
0.001; R2lik = 16.92%, ΔlogLik = 14.8, P< 0.001; Fig 5), while phylogeny and plant height explained
variation in seed mass of species of other monocots and dicots
(R2lik = 42.91%, ΔlogLik = 78.2, P <
0.001; R2lik = 6.36%, ΔlogLik = 9.2, P< 0.001; R2lik = 33.81%, ΔlogLik = 330.5,P < 0.001; R2lik = 7.32%, ΔlogLik =
60.9, P < 0.001; Fig 5). Phylogeny rather than leaf
size explained a majority of variation in seed mass in gymnosperms
(R2lik = 16.35%, ΔlogLik = 3.6, P = 0.008;
R2lik = 8.51%, ΔlogLik = 1.8, P = 0.059; Fig
5).