Ecological and phytochemical diversity of arillate seeds inAglaia(Meliaceae): a study of vertebrate dispersal in tropical trees

Abstract

The dispersal of ten species of equatorial rainforest tree, belonging to the genusAglaia, was studied in Malaysia and Indonesia. In three of these (Aglaiaspecies 2,A. oligocarpaandA. teysmanniana) the fruits are dehiscent capsules and the red-skinned arillate seeds are dispersed by birds. Nine species of bird, belonging to six families (Bucerotidae, Capitonidae, Corvidae, Eurylaimidae, Pycnonotidae and Sturnidae), were observed to swallow the seeds. The fruits of the remaining species are indehiscent and the seeds have a white, yellow or translucent aril. The seeds of five species (A. elliptica,A. odoratissima,A. speciosa,A. korthalsiiandA. ganggo) are dispersed by primates (includingPongo pygmaeus,Hylobates lar,Presbytis melalophusandMacaca fasicularis) and one species (A.aff.elaeagnoidea) by a civet (Paradoxurus hermaphroditus). Several species of squirrel feed on the seeds, but are thought not to be important dispersers. Published accounts suggest that pigeons (Columbidae) in West Malesia, and birds of paradise (Paradisaeidae) and cassowaries (Casuariidae) in Australasia, are also dispersal agents. The arils of six of theseAglaiaspecies and four species belonging to other genera (Tabernaemontana macrocarpa,Zingibersp.,Lansium domesticumandDurio zibethinus) were analysed for lipids, carbohydrates and amino acids. A high lipid content (27-60% dry mass) was found in arils of the bird-dispersedAglaiaseeds, those of primate-dispersed species were lower in lipids and higher in free carbohydrates (reducing sugars and sucrose).