Pollinator Shifts (pollinator + shift)

Distribution by Scientific Domains


Selected Abstracts


Pollinator shifts and the loss of style polymorphism in Narcissus papyraceus (Amaryllidaceae)

JOURNAL OF EVOLUTIONARY BIOLOGY, Issue 6 2010
R. PÉREZ-BARRALES
Abstract Darwin proposed that the driving force for the evolution of style polymorphisms is the promotion of cross-pollination between style morphs, through accurate placement of pollen on the pollinator's body. This hypothesis has received much attention, but the effect of different pollinators in the fitness of morphs remains poorly understood. Narcissus papyraceus is a style dimorphic species (long -L- and short -S- styled) with isoplethic (1 : 1) and L-monomorphic populations, mainly visited by long-tongued (LT) nocturnal and short-tongued (ST) diurnal pollinators, respectively. We studied natural female fertility of morphs, and assessed the role of diurnal and nocturnal pollinators. We also quantified female fertility of the morphs in experimental populations with different morph ratio, exposed to predominately long- or short-tongued pollinators. We found that with LT pollinators, both morphs were successfully pollinated in all morph ratio conditions, suggesting that these insects could be involved in maintenance of the polymorphism, although other factors may also play a role. However, with ST pollinators, S-plants displayed less fertility than L-plants, and mating among L-plants was favoured, implying that the polymorphism is lost. These results underscore the role of pollinators on variations in style polymorphism. [source]


Pollen presentation and pollination syndromes, with special reference to Penstemon

PLANT SPECIES BIOLOGY, Issue 1 2000
James D. Thomson
Abstract Pollen presentation theory (PPT) allows for a re-examination of some classic themes in pollination biology. Here, we outline its implications in the context of bee- and bird-adapted species of Penstemon and Keckiella (Scrophulariaceae). PPT models the optimal schedule of pollen presentation, based on the frequency of visits by pollinators, and the capacities of those pollinators to remove and deposit pollen. High visitation rates, high removal and low deposition all favor plants that present pollen in many small doses. Dosing is achieved through gradual opening of anthers and through anthers opening only narrowly. We hypothesize that bees have higher rates of removal and lower rates of deposition than birds; therefore, bee-pollinated species should have anthers that open more gradually and less completely than bird-pollinated species. Before presenting preliminary results that affirm this prediction, we critically discuss the characterization of species by pollination syndrome. PPT sheds new light on why plants may specialize on particular pollinators. Stebbins' most effective pollinator can be recast as the pollinator that deposits more of the pollen that it removes, thereby making other visitors into conditional parasites. Pollinator shifts might occur when a pollinator with low removal and high deposition becomes abundant; the plants would then be selected to discourage their previous pollinators who are now parasites. Bird-pollination may favor anthers that open quickly and widely, thereby making bees wasteful parasites. Bee-pollination may favor anthers that open slowly and narrowly, thereby making birds ineffective pollinators. In paired comparisons of closely related species, the hummingbird-visited species were redder, had narrower or longer floral tubes, more exserted anthers and stigmas, less pronounced landing platforms, more inclined orientation, produced more nectar of a lower concentration, and had anthers that dehisce faster and more extensively. [source]


Genetic patterns and pollination in Ophrys iricolor and O. mesaritica (Orchidaceae): sympatric evolution by pollinator shift

BOTANICAL JOURNAL OF THE LINNEAN SOCIETY, Issue 4 2009
PHILIPP M. SCHLÜTER
Ophrys iricolor and O. mesaritica are a pair of morphologically similar, closely related sexually deceptive orchids from the eastern Mediterranean. Ophrys iricolor is known to be pollinated by Andrena morio males and the specific pollinator of Ophrys mesaritica is determined as Andrena nigroaenea. Amplified fragment length polymorphism revealed O. iricolor and O. mesaritica to be genetically intermixed on the whole, although populations of O. iricolor and O. mesaritica in geographical proximity are strongly differentiated, suggesting that specific pollinators locally differentiate these taxa. Based on the available biological data and the system of pollinator attraction operative in Ophrys, we hypothesize that O. mesaritica may have arisen from O. iricolor by pollinator shift and that this is more probable than scenarios invoking hybridization as a result of mispollination by rare, non-specific flower visitors or specifically attracted insects. © 2009 The Linnean Society of London, Botanical Journal of the Linnean Society, 2009, 159, 583,598. [source]