title: Transition from wind pollination to insect pollination in sedges: experimental evidence and functional traits.
abstract: Transitions from wind pollination to insect pollination were pivotal to the radiation of land plants, yet only a handful are known and the trait shifts required are poorly understood. We tested the hypothesis that a transition to insect pollination took place in the ancestrally wind-pollinated sedges (Cyperaceae) and that floral traits modified during this transition have functional significance. We paired putatively insect-pollinated Cyperus obtusiflorus and Cyperus sphaerocephalus with related, co-flowering, co-occurring wind-pollinated species, and compared pairs in terms of pollination mode and functional roles of floral traits. Experimentally excluding insects reduced seed set by 56-89% in putatively insect-pollinated species but not in intermingled wind-pollinated species. The pollen of putatively insect-pollinated species was less motile in a wind tunnel than that of wind-pollinated species. Bees, beetles and flies preferred inflorescences, and color-matched white or yellow models, of putatively insect-pollinated species over inflorescences, or color-matched brown models, of wind-pollinated species. Floral scents of putatively insect-pollinated species were chemically consistent with those of other insect-pollinated plants, and attracted pollinators; wind-pollinated species were unscented. These results show that a transition from wind pollination to insect pollination occurred in sedges and shed new light on the function of traits involved in this important transition.
authors.affiliation: School of Biological and Conservation Sciences, University of KwaZulu-Natal, Private Bag X01, Scottsville 3209, South Africa.|Present address: Department of Ecology, Evolution, and Behavior, University of Minnesota, 100 Ecology Building, 1987 Upper Buford Circle, St. Paul, MN 55108, USA.
authors.forename: Peter D
authors.initials: PD
authors.lastname: Wragg
authors.affiliation: School of Biological and Conservation Sciences, University of KwaZulu-Natal, Private Bag X01, Scottsville 3209, South Africa.
authors.forename: Steven D
authors.initials: SD
authors.lastname: Johnson
mesh_terms: D000818:Animals; D003116:Color; D029786:Cyperus / Q000737:chemistry / Q000254:growth & development / Q000502:physiology*; D056626:Inflorescence / Q000502:physiology; D007313:Insecta / Q000502:physiology*; D009812:Odorants / Q000032:analysis; D011058:Pollen / Q000502:physiology; D054817:Pollination; D012639:Seeds / Q000254:growth & development / Q000502:physiology; D014919:Wind