Abstract Detail

Ecological Section

Kaczorowski, Rainee L. [1], Gardener, Mark C. [2], Holtsford, Timothy P. [1].

Nectar traits and availability in Nicotiana, Section Alatae (Solanaceae) in relation to primary pollinators and mating system.

Nicotiana, Section Alatae exhibits great diversity among species in morphology, mating system, and primary pollinators. As a first step towards a larger goal of estimating nectar's role in floral evolution, we studied several nectar traits within the eight species of Nicotiana, Section Alatae, to determine whether they vary in association with primary pollinators and mating system. Daily phenology determines when nectar becomes available to pollinators and was shown to differ between hummingbird- and moth-pollinated species. Nectar volume increased significantly in all species, except putative species “Rastroensis”, over the first 24 hours after anthesis and was positively correlated with corolla length. Nectar concentration (determined through refractometer readings) increased significantly over the first 24 hours after anthesis within the hummingbird- and small moth-pollinated species, but did not increase significantly within the hawkmoth-pollinated species, and was negatively correlated with corolla length. Nectar volumes and concentrations varied significantly among most species and pollinator groups. Since nectar volume and concentration were negatively correlated, total energy was more similar among species and across corolla lengths. The autogamous species, N. plumbaginifolia, had a nectar volume that matched expectations based on corolla length, but with lower concentration and total energy than predicted by corolla length. Sugar and amino acid components (determined through HPLC) were found to be more similar among species, although differences did exist. The nectar of most species was sucrose-dominant, but the autogamous N. plumbaginifolia had nectar that was close to being balanced. Many of the nectar traits examined were shown to vary in association with the primary pollinators and, in some cases, mating system.

1 - University of Missouri-Columbia, Biological Sciences, 105 Tucker Hall, Columbia, Missouri, 65211, USA
2 - Open University, Biolgical Sciences, Walton Hall, Milton Keynes, Buckingham, MK7 6AA, UK

Keywords:
amino acids
energy
nectar
Nicotiana
pollinators
sugars
volume
concentration
mating system.

Presentation Type: Paper
Session: 17-8
Location: Wasatch (Cliff Lodge)
Date: Monday, August 2nd, 2004
Time: 3:15 PM
Abstract ID:333