Abstract Detail

Pollination Biology

Leege, Lissa M. [1], Irwin, Rebecca E. [2], Adler, Lynn S. [3].

Local adaptation to florivory and nectar robbing in the distylous vine, Gelsemium sempirvirens.

Floral traits that attract insect pollinators also attract antagonists that feed on flowers and rob nectar rewards. Florivores and nectar robbers may reduce plant fitness by damaging sexual organs and reducing floral attractiveness and nectar rewards. The goal of this study was to determine the genetic basis and possible mechanisms for resistance to antagonists, and whether resistance traits reduce interactions with mutualists. To examine the effects of nectar robbers and florivores on pollination and plant fitness, we studied the insect-pollinated native perennial vine, Gelsemium sempervirens (Carolina Jessamine, Loganiaceae), which is frequently nectar-robbed in north Georgia, USA and attacked by a florivore in south Georgia. We conducted common-garden experiments in north and south Georgia, using cloned genotypes from populations in each region. We measured resistance to robbing and florivory, attraction of pollinators, and plant reproduction in each common garden to test the contributions of region of origin and environment to resistance to robbers and florivores, whether resistance to either antagonist affects pollinator attraction, and how resistance affects fitness. We also measured floral morphology and alkaloids to elucidate potential mechanisms of resistance.
Strong local adaptation was evident in nearly all the traits we measured, though environment did play a role. Nectar robbing was >4 times as common in the north garden than in the south. Consistent with the higher intensity of nectar robbing in the north, northern plants had smaller flowers and higher leaf alkaloid concentrations and had one-third as many pollinator visits as southern genotypes. They were half as likely to be nectar-robbed as southern genotypes, however. Lower visitation rates translated into lower fitness: northern genotypes produced one-third as much fruit and seed as did southern genotypes. Environment also affected fruit production: fruit production was almost twice as high in the south as in the north. This study demonstrates local adaptation to floral antagonists, and suggests significant fitness consequences of resistance to nectar robbers.

Broader Impacts:

1 - Georgia Southern University, Biology, P.O. Box 8042, Statesboro, GA, 30460, USA
2 - Dartmouth College, Department of Biological Sciences, Gilman Lab, Hanover, New Hampshire, 03755, USA
3 - University of Massachusetts, Dept of Plant, Soil & Insect Science, 102 Fernald Hall, 270 Stockbridge Rd., Amherst, MA, 01003

Keywords:
nectar robbing
gelsemine
resistance to antagonists
local adaptation
Florivory.

Presentation Type: Oral Paper:Papers for Topics
Session: 48
Location: 551B/Convention Center
Date: Wednesday, August 4th, 2010
Time: 8:15 AM
Number: 48002
Abstract ID:282