Microclimate and Individual Variation in Pollinators: Flowering Plants are More than Their Flowers

Abstract

JSTOR is a not-for-profit service that helps scholars, researchers, and students discover, use, and build upon a wide range of content in a trusted digital archive. We use information technology and tools to increase productivity and facilitate new forms of scholarship. For more information about JSTOR, please contact support@jstor.org. Abstract. Variation in pollinator composition at the individual plant level is an important prerequisite for plant specialization on pollinators that does not seem to have been investigated previously. I studied variation in pollinator composition in a southeastern Spanish population of the insect-pollinated shrub Lavandula latifolia (Labiatae) and examined its correlates, with particular reference to the distinction between factors intrinsic (flower morphology, nectar standing crop, size of floral display) and extrinsic (sunlight regime, ambient temperature, humidity) to the plants. L. latifolia shrubs differed significantly in all intrinsic variables measured, in average irradiance levels (due to site-dependent variation in timing and duration of insolation periods), and in pollinator composition at both the species and order levels. Individual variation in pollinator composition was largely due to differences among insect taxa in their foraging responses to the sunlight mosaic. While some pollinators foraged indiscriminately over that mosaic, others preferred sites characterized by high irradiance. Variation among plants in intrinsic variables was unrelated to differences in pollinator composition, which depended significantly only on the sunlight regime associated with each plant's location in the habitat. Site-specific effects in pollination will generally act to reduce the likelihood of selective pressures by animals on plant traits. Their importance should be greatest in habitats characterized by patchiness in environmental variables that affect pollinator behavior and in plants with pollinator assemblages dominated by ectothermic species. Ecological Society of America

Reproductive biology of Davilla kunthii A. St-Hil. (Dilleniaceae) in Central Amazonia

“…4) illustrates the interactions between sample groups and visiting bees, clearly showing the shared and the exclusive bee species in the four sample groups of D. kunthii. Th e existence of unique species (visitors of only one sample group) is in agreement with the perspective that oscillations in the composition of the visiting guild depends more upon the characteristics of each species of visitor (Ramalho et a.l 1994(Ramalho et a.l , 1998Herrera 1995;1997) and especially upon agonistic interactions and the proximity of the fl oral source to the nesting sites of the bees (Hilário et al~. 2000;Kajobe et al 2007).…”

“…Concerning competition for food sources, there may be behavioural and physiological alterations among species: diff erences in foraging time, varying distribution through resource patches and even agonistic interactions that may lead to food source monopolisation (Roubik 1989;Herrera 1995;1997;Ramalho et al 2004).…”

“…Th e causes that govern interpopulation variation of pollinators for a certain plant species, which consequently promote generalised pollination systems, are diverse. Th ese causes may be nested according to the ecophysiological requirements of the pollinator (Ramalho et a.l 1994;Herrera 1995;1997;Hilário et al 2000;Kajobe et al 2007), plant population size (Eckhart 1991;Conner & Neumeier 1995;Roll et al 1997), and competition with more sympatric species (Caruso 2000).…”

Reproductive biology and pollination of Aechmea distichantha Lem. (Bromeliaceae)

“…Environmental variation may also infl uence fi tness by aff ecting the number and abundance of pollinating species (Herrera 1995). In the Bromeliaceae, environmental variation can infl uence reproductive success within and among populations (Paggi et al 2007).…”

Consecuencias de las variaciones microclimáticas sobre la visita de insectos polinizadores en dos especies de Chaetanthera (Asteraceae) en los Andes de Chile central

“…Rozzi (1990), y posteriormente Rozzi et al (1997) encontraron que dichas variaciones microclimáticas están asociadas a cambios en los ensambles de polinizadores de Anarthrophyllum cumingii y Chuquiraga oppositifolia, lo cual puede afectar el flujo génico entre individuos que habitan en INTRODUCCIÓN Ha sido ampliamente documentado que la visita de los polinizadores a una planta puede ser afectada por factores bióticos como la densidad de flores en un parche (Schaal 1978, Thompson 1981, Schmitt 1983, Waser & Price 1983, Sih & Baltus 1987, Watkins & Levin 1990) o el despliegue floral de las especies (e.g., Kannitz & Maun 1991, Karron et al 2004, Grindeland et al 2005. No obstante, factores abióticos tales como las condiciones microclimáticas imperantes en el sitio donde se encuentran las plantas, también pueden influir fuertemente sobre el comportamiento y la actividad de los polinizadores (Herrera 1995a, 1995b, Rozzi et al 1997. Los polinizadores son especialmente sensibles a cambios de temperatura, velocidad del viento y nubosidad.…”