| do floral syndromes predict specialization in plant pollination systems? an experimental test in an "ornithophilous" african protea. | we investigated whether the "ornithophilous" floral syndrome exhibited in an african sugarbush, protea roupelliae (proteaceae), reflects ecological specialization for bird-pollination. a breeding system experiment established that the species is self-compatible, but dependent on visits by pollinators for seed set. the cup-shaped inflorescences were visited by a wide range of insect and bird species; however inflorescences from which birds, but not insects, were excluded by wire cages set few see ... | 2004 | 15168105 |
| botany: specialized bird perch aids cross-pollination. | birds may hover over or perch on flowers when feeding on nectar, and this assists cross-pollination if they then visit other plants. here we investigate the curious sterile inflorescence axis of the south african cape endemic 'rat's tail' plant (babiana ringens, iridaceae), whose function--unlike in other bird-pollinated plants--is exclusively to provide a perch for foraging birds. we find that this structure promotes the plant's mating success by causing the malachite sunbird (nectarinia famosa ... | 2005 | 15875009 |
| the impact of pollination syndrome and habitat on gene flow: a comparative study of two streptocarpus (gesneriaceae) species. | gene flow through pollen and seed dispersal is important in terms of population differentiation and eventually speciation. seed and pollen flow are affected in turn by habitats and pollen vectors. we examined the effect of different pollinators and habitats on gene flow by comparing two species of streptocarpus, using microsatellite and chloroplast rflp markers. populations of the forest-dwelling s. primulifolius were highly differentiated according to nuclear microsatellite data and had mutuall ... | 2007 | 21636365 |
| sugar digestion efficiencies of gurney's sugarbirds, malachite sunbirds, and black sunbirds. | this study determined the interaction between energy assimilation and digestive constraints on the foraging behaviour of nectarivorous gurney's sugarbirds (promerops gurneyi), black sunbirds (nectarinia amethystina), and malachite sunbirds (nectarinia famosa) in the laboratory. rates of sugar intake and consumption, transit time, and the concentration of sugar in the excreta were measured when birds were fed 0.25 mol l-1 sucrose, 0.73 mol l-1 sucrose, and 0.73 mol l-1 glucose. for each species, ... | 2013 | 9231381 |
| do pollinator distributions underlie the evolution of pollination ecotypes in the cape shrub erica plukenetii? | according to the grant-stebbins model of pollinator-driven divergence, plants that disperse beyond the range of their specialized pollinator may adapt to a new pollination system. although this model provides a compelling explanation for pollination ecotype formation, few studies have directly tested its validity in nature. here we investigate the distribution and pollination biology of several subspecies of the shrub erica plukenetii from the cape floristic region in south africa. we analyse th ... | 2014 | 24071499 |
| can short-billed nectar thieving sunbirds replace long-billed sunbird pollinators in transformed landscapes? | pollinator specialisation through exploitation barriers (such as long floral tubes) does not necessarily mean a lack of pollination when the favoured pollinator is rare or absent. theory predicts that suboptimal visitors will contribute to plant reproduction in the absence of the most effective pollinator. here i address these questions with chasmanthe floribunda a long-tubed plant species in the cape floristic region, which is reliant on one species of pollinator, the long-billed malachite sunb ... | 2016 | 27219484 |
| geographic variation of reproductive traits and competition for pollinators in a bird-pollinated plant. | geographic variation in the reproductive traits of animal-pollinated plants can be shaped by spatially variable selection imposed by differences in the local pollination environment. we investigated this process in babiana ringens (iridaceae), an enigmatic species from the western cape region of south africa. b. ringens has evolved a specialized perch facilitating cross-pollination by sunbirds and displays striking geographic variation in perch size and floral traits. here, we investigate whethe ... | 2019 | 31673331 |