Specialization for hawkmoth and long-proboscid fly pollination in Zaluzianskya
section Nycterinia (Scrophulariaceae) |
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Authors: | S D JOHNSON J EDWARDS CARBUTT C POTGIETER |
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Institution: | School of Botany and Zoology, University of Natal, Private Bag X01, Scottsville, Pietermaritzburg, 3209, South Africa |
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Abstract: | The evolution of pollination systems has been investigated in Zaluzianskya section Nycterinia (Scrophulariaceae), a group characterized by very long-tubed flowers (up to 60 mm) that open either only at night (19 species) or during the day (one species). Field observations of three species: Z. natalensis , Z. elongata and Z. pulvinata , revealed that their flowers are pollinated shortly after dusk by hawkmoths. Further observations showed that Z. microsiphon , the sole species to have flowers that open only during the day, is pollinated exclusively by long-proboscid flies belonging to the family Nemestrinidae. A phylogenetic analysis of Z. sect. Nycterinia based on morphological characters indicates that Z. microsiphon evolved within a clade of night-flowering species. The shift from hawkmoth to long-proboscid fly pollination in Zaluzianskya was probably facilitated because long corolla tubes, white petals and dilute nectar in hawkmoth-pollinated flowers are pre-adaptations for pollination by long-proboscid flies. However, the autapomorphic features of Z. microsiphon , such as zygomorphy, diurnal flower anthesis and lack of scent, can be regarded as adaptations for long-proboscid fly pollination. Breeding system experiments on Z. natalensis and Z. microsiphon revealed the existence of genetic self-incompatibility. © 2002 The Linnean Society of London, Botanical Journal of the Linnean Society , 138 , 17–27. |
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Keywords: | adaptive radiation flora of southern Africa nectar Nemestrinidae phylogeny self-incompatibility Sphingidae |
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