Allometry and the distribution of fruit and seed traits across tropical plant species

Abstract

Fruit and seed morphometry was studied across 1070 plant species belonging to 140 families from 27 contrasting plant communities. The main objectives were to identify allometric relationships and describe the frequency distributions of the weights and sizes of fruits and seeds across plant species, regardless of any qualitative attribute or community type. The frequency distributions of 12 morphometric variables were then determined. Pearson correlations were used to describe associations between quantitative attributes and estimate the slopes of the lines (allometric coefficients) obtained. In general, small fruits and seeds (<1 cm) prevailed in the sample examined. The frequency distributions of the weight and size parameters of the fruits and seeds were bell-shaped, with the exception of the number of seeds per fruit, which was skewed to the right. The highest allometric coefficients were found between the dry weights and sizes of the fruits and seeds, suggesting that these traits are mutually supporting. The cost of seed packaging per fruit, or the pericarp/seed ratio, tended to decrease with increasing investment in progeny, and the number of seeds per fruit decreased with an increase in seed weight. The significant associations between the fruit shape indexes and the morphometric attributes show that the shape of fruits is related to their size and weight. The highest allometric coefficients were found between the dry weights and sizes of the fruits and seeds. Fruit and seed size can predict their biomass and vice versa. There is a close relationship between fruit biomass values and their components (seeds and pericarp). Most species invest more biomass in pericarp (protection and dispersal) compared with the investment in progeny (seed per fruit). The sample examined could be influenced taxonomically along with selective pressures that favour the reproductive economy of the species and suggest that morphometric traits have evolved in coordination.