4 resultados para FLOWER VISITOR WEBS
em Digital Archives@Colby
Resumo:
The word “wilderness” in America is generally identified with pristine places where humans are not among the primary influences on the land and its ecology. The American wilderness ethic creates a strict dichotomy between humans and nature. The Wilderness Preservation Act of 1964 defines wilderness as “an area where the earth and its community of life are untrammeled by man, where man himself is a visitor who does not remain” (wilderness.net). This statutory definition of wilderness is essentially the functional embodiment of the American wilderness ethic. Wilderness can also be interpreted in ways that incorporate humans as active players in the natural world. Land which is managed for human use but is uninhabited can be considered wilderness to some degree because “man himself is a visitor who does not remain.” Wilderness, especially in the Northeast, can be visualized based on different land use characteristics. Conservation in the Northeast requires a redefinition of wilderness in order to incorporate land that has been utilized by humans.
Resumo:
Pollinator visitation rates over the life of a flower are determined by pollinator abundance and floral longevity. If flowers are not visited frequently enough, pollen limitation may occur, favoring the evolution of self-compatibility (SC). In plant species with varying SC levels, central populations often are self-incompatible (SI) and peripheral populations are SC. Witheringia solanacea (Solanaceae) is a species that follows this trend with the exception of one population in the Monteverde Cloud Forest Reserve, which is peripheral yet SI. I investigated this population using multiple techniques including floral bagging, pollinator observations, microsatellite analysis, and floral longevity manipulations. My results confirmed the self-incompatibility of the Monteverde population and indicated low but perhaps adequate rates of pollinator visitation per flower per hour. I found reduced genetic diversity at Monteverde and gene flow occurring unidirectionally from San Luis (a central population) to Monteverde. In the greenhouse, there was more of an effect of male than female function on floral longevity, but the largest differences were environmental. Flowers stayed open substantially longer when cool, cloudy weather was simulated and shorter when conditions were hot and sunny. The results indicate that the Monteverde population of W. solanacea is SI because 1) it is unable to maximize its fitness due to gene flow from San Luis and its relatively recent colonization of the area and 2) pollen limitation may not be severe because of supplemental pollinator availability from other Witheringia species in the area and increased floral longevities due to cool and cloudy conditions.