Characteristics of the vertebrate-dispersed fruits of sixteen Northern Territory monsoon forest tree species

Abstract

The monsoon forests of the Top End of the Northern Territory contain an unusually high proportion of tree species with vertebrate-dispersed fruits, but the corresponding fauna is disproportionately species-poor. We document and compare the morphology, moisture content, nutrient content and crop size of sixteen common fleshy- or arillatefruited tree species from the region. Arils were much richer in lipids and lower in carbohydrates than fleshy fruits. A gradient of flesh nutrient contents from high levels of carbohydrates to high levels of nutrients that are more costly for the plant to produce was identified. However, this gradient was not related to other fruit characters, providing only weak support for the generalist-specialist paradigm in the evolution of vertebrate-dispersed fruits. Evidence was obtained of a trade-off between the size and number of fruits. Compared to other tropical regions, the flesh of the species sampled was high in carbohydrates and low in costly nutrients.