Cover illustration: The inset cover photograph shows Bombus dahlbomii entering the flower of an advanced-generation hybrid from a Mimulus luteus var. luteus x M. naiandinus hybrid swarm in central Chile. Flower colour divergence amongst the hybrids is not associated with pollinator divergence, with factors such as mating system probably playing a more important role. See Cooley et al. (pp. 641-650).
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