The fruit syndrome hypothesis posits that the evolution of fruit traits is driven by frugivore sensory ability, behavior and physiology. However, given the diversity of dispersers and disperser sensory phenotypes, it is unlikely that fruits exhibit disperser-specific attractants. Despite the unlikelihood of fruit specialization on a given disperser species, suites of fruit traits may evolve along certain axes based on broad sensory adaptations of frugivores guilds. One potentially critical axis is the dichotomy between visually-oriented and olfactory-oriented disperser guilds. Here, we evaluate the visual and olfactory attractants produced by endemic Malagasy fruits in tropical dry forest (N=57) in a phylogenetically controlled analysis, using spectroscopy and gas chromatography-mass spectrometery.
Results/Conclusions
We demonstrate that plants invest in dichotomous signaling strategies according to two different disperser guilds: olfactorily-oriented foragers, and visually-oriented foragers, and that these plant traits are not phylogenetically constrained. Chromatically conspicuous fruits tend not to be odiferous, and odiferous fruits tend not to be chromatically conspicuous. Plants that invest in color converge upon the production of the same fruit color – blue. This is particularly interesting given that blue is one of the only visually salient colors discernible against a background of leaves for every seed dispersing animal in the study system.