Plant/Pollinator Interactions in Fragmented Landscapes
Skogen, Krissa A. , Raguso, Robert A. , Fant, Jeremie , Hilpman, Evan T. .
Hawkmoth pollination of Oenothera in a fragmented landscape – variation in scent, floral morphology, nectar and neutral genetic markers.
Habitat fragmentation can have important consequences for both plant and pollinator populations. For plant species that rely on long-distance pollinators (e.g. hawkmoths) for reproductive success, habitat fragmentation may alter population genetic patterns in distinct and predictable ways. Floral cues to which pollinators respond, including floral morphology, scent chemistry and nectar sugar concentrations, may change in fragmented areas due to restricted gene flow and increased inbreeding in the resultant small, isolated populations. We present data from two field seasons and associated laboratory results aimed at understanding whether fragmentation negatively impacts a self incompatible species primarily pollinated by a long distance disperser. Our study species is Oenothera harringtonii (Harrington’s evening primrose, Onagraceae), an annual endemic to southeastern Colorado that occurs in a landscape increasingly fragmented by human activities. The showy, night-blooming flowers of O. harringtonii are pollinated primarily by hawkmoths, and secondarily by matinal bees. Because O. harringtonii is a self incompatible annual, the genetic consequences of habitat fragmentation might be expected to be seen in just a few generations. Here, we discuss differences in population size (vegetative and reproductive) and density of flowering individuals, pollinator visitation rates, floral advertisements (morphology, scent chemistry) and rewards (nectar sucrose concentration) and neutral genetic variation in fragmented and unfragmented populations. We report lower hawkmoth visitation rates in fragmented areas when compared to unfragmented areas. However, preliminary microsatellite data indicate that while levels of inbreeding are high, fragmented populations are not differentiated from unfragmented populations, and gene flow among all populations is high, with only about one percent of the diversity due to differences among populations. We also present data on patterns of variation in floral fragrance to determine if population-level patterns depart from the null expectations of neutral genetic variation. The scent chemistry of O. harringtonii shows enough qualitative and quantitative variation in scent composition to provide an excellent test of the impact of fragmentation on traits linked to pollinator attraction.
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1 - Chicago Botanic Garden, Division of Plant Science and Conservation, 1000 Lake Cook Road, Glencoe, IL, 60022, USA
2 - Cornell University, Department of Neurobiology and Behavior , W355 Seeley G. Mudd Hall, Ithaca, NY, 14853, USA
3 - Chicago Botanic Garden, Plant Science and Conservation, 1000 Lake Cook Road, Glencoe, IL, 60022, USA
4 - Colorado College, Biology Department, Colorado Springs, CO, 80903 , USA
Presentation Type: Symposium or Colloquium Presentation
Location: 552B/Convention Center
Date: Wednesday, August 4th, 2010
Time: 1:45 PM