Griffin, Adam , Webster, Amanda , Byers, Diane .
Living in a Fragmented Landscape: Pollinators and the Consequences for Reproduction in Lobelia spicata.
Fragmented landscapes may negatively affect mutualistic relationships among species, such as plant-pollinator interactions. Plants with gynodioecious breeding systems (plants with female or hermaphroditic flowers) depend on pollinator visits for any seed by females, and for outcrossed seed production by hermaphrodites. Lobelia spicata, a gynodioecious plant, occurs in hill and tallgrass prairies. Today its habitat ranges from small and isolated to large and less isolated sites. Unlike hermaphroditic flowers, female flowers of L. spicata do not produce nectar as a reward, and instead rely on mimicking hermaphroditic flowers to provoke visitations. Thus we expect the visitation rate to hermaphrodites to be greater than to females. To test this we observed pollinator behavior and quantified seed production in a small, isolated tallgrass natural prairie near Weston, Illinois. After determining the sex of 100 plants, visitor behavior was assessed during 20-minute observations to determine the total number of visits, time spent, and number of flowers by each visitor. Visitors included mason bees, honeybees, sweat bees, several butterfly species and a species of hawk moth. Three fruits from each plant were collected for assessing seed production. Visitor observations showed no difference in total number of visits between females and hermaphrodites, but the number of flowers visited and time spent on the plant was significantly higher in hermaphrodites. Seed production, which was much higher in female plants, did not reflect visitor behavior. Given that female plants obtain all of their fitness through seed production, they should produce twice the seed production. The seed production for female plants was less than expected. Compared to populations located in larger and less isolated prairies, both sexes at Weston were more variable in their seed production.
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1 - Illinois State University, School of Biological Sciences, Campus Box 4120, Normal, IL, 61790, USA
2 - Illinois State University, School of Biological Sciences, Campus Box 4120, Normal, IL, 61790-4120, USA
Presentation Type: Oral Paper:Papers for Topics
Location: Wasatch A/Cliff Lodge - Level C
Date: Monday, July 27th, 2009
Time: 3:00 PM