Primate-Plant Interactions in the Tropical Dry Forests of Northwestern Madagascar: Seed Dispersal and Sensory Ecology of Eulemur fulvus

Fruiting plants and frugivores are involved in a complex set of interactions. Frugivores rely on fruiting plants as critical food resources, while fruiting plants rely on frugivores for seed dispersal services. Here, I measure the interrelatedness of brown lemurs (Eulemur fulvus) and the endemic fruits they disperse in the tropical dry forests of Ankarafantsika National Park, northwestern Madagascar. I analyze fruit traits across all fruits consumed by brown lemurs over the course of one year of behavioral study of three groups of habituated, individually identifiable brown lemurs. Using non-invasive genetic sampling, I determine that brown lemurs are dichromatic, or red-green color blind. Using spectroscopy, I quantify fruit color, and model it according to the brown lemur dichromatic phenotype and known optical morphology. I additionally quantify fruit puncture resistance using a modified force gauge and fruit odor using XAD filtration and gas chromatography-mass spectrometry. I determine that many ripe fruits colors are conspicuous to brown lemurs against a background of leaves, and that ripe fruits are significantly different chromatically from unripe fruits. I also determine that ripe fruit odors are significantly higher in ripe versus unripe fruits, and that during foraging, fruit odor and fruit size are the two strongest determinants of brown lemur foraging behavior and efficiency. Understanding the degree of fruit-frugivore interrelatedness is critical in the dry forests of Madagascar, where habitat and species loss is proceeding at a rapid pace.