PHYLOGENETIC PATTERNS AMONG TROPICAL FLOWERING PHENOLOGIES

1 The ability of phylogenetic, water stress and 'shared-pollinator' hy potheses to explain flowering times was tested for the flora of Barro Colorado Island, Panama. Both quantitative (217 species) and qualitati ve (1173 species) flowering data were used. 2 Descriptive metrics calc ulated from quantitative flowering data indicated that mean flowering times fell in the final two months of the dry season and the first two months of the wet season for 56% of species and that flowering was co ncentrated in a short, predictable part of the year for the great majo rity of species. 3 The 'shared-pollinator' hypothesis predicted that c ongeners should have temporally segregated flowering times. This hypot hesis was rejected for 57 of 59 genera. 4 The water stress hypothesis predicted that species from drier habitats and life forms with limited access to soil water should flower in the wet season. This hypothesis was also rejected. 5 There were, however, strong phylogenetic pattern s. Both the mean and the variance of flowering times were similar amon g congeners. The variance of flowering times was also similar among co nfamilials, and mean flowering times were concentrated in the wet seas on for monocotyledons.