Effects of Floral Morphology, Temperature, Date, Time, and Population Origin on Pollinator Visitation to the Wild Radish , Raphallus rapluinistrum
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Floral morphology is an important component of fitness in insect pollinated plants. For plants that rely on animals for pollination, such as Raphanlls raphallislrunl, the effect floral morphology has on the number of flowers probed and amount of time spent by pollinators during visitation can be a crucial determinant of fitness. In this study, two floral characteristics (petal width and petal length) were measured in order to calculate average petal area and petal asymmetry (average left petal area - average right petal area). 5 other variables were recorded; the number of flowers open, plant height, time of day, date, and air temperature. Relationships between these variables were analyzed and compared with visitation rates for 3 different pollinator taxa consisting of Diptera (Syrphidae only), Hymenoptera, and Lepidoptera. In addition, comparison of pollinator visitation rates between two R. raphanislunl populations from different geographic regions were made to find out if the populations differed enough to affect the pollinator's visitation rates and duration. Pollinators were also collected, identified, and compared with pollinator compositions from previous R raphallislrllnl study sights. The two populations varied slightly in average petal area, petal asymmetry, number of flowers open, and plant height. There were no significant differences in the pollinator's reactions to the two populations. In general, pollinator visitation increased with increasing number of flowers open and average petal area. Pollinator visitation decreased later in the season. The 3 taxa of pollinators responded differently to the effects of petal symmetry and time of day. Ambient temperature and the height of the plant had no effect on the pollinators.