Pollinator specificity facilitates reproductive isolation among plants, and mechanisms that generate specificity influence species boundaries. Wang et al. use two varieties of an Asian fig tree, Ficus semicordata, that are host to two different Ceratosolen wasp pollinators to investigate mechanisms of pollinator specificity among sympatric, closely related taxa. They find that only one of the wasps displays a preference between the different receptive-phase floral scents of the two fig varieties, and that specificity is reinforced by physical contact cues on the surface of the plants. When pollinators enter atypical hosts, post-zygotic factors reduce but do not prevent the production of hybrid offspring.
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