Rainee Kaczorowski

Rainee Kaczorowski

Rainee collecting nectar & estimating its concentration of dissolved solids with a refractomoter.

Rainee is working on nectar chemistry in Nicotiana Section Alatae. Correlations between nectar characteristics and pollinator preferences have been found by many other researchers. I am seeking to find out whether nectar traits in Nicotiana influence pollinator preferences.

Different pollinators have been observed visiting the different species of Nicotiana. Hawkmoths are the primary pollinators of N. longiflora, N.plumbaginifolia, and N. alata. Hummingbirds are the primary pollinators of N. langsdorfii, N. forgetiana, and N. mutabilis, although other pollinators have also been noted. Small perching moths that do not hover but land on the lower lobes of the flowers are the primary pollinators of N. bonariensis. We would like to look at the differences in nectar constitution between the moth-pollinated species vs. the species pollinated by hummingbirds and other pollinators, and between the hawkmoth vs. small moth species. Another interesting trait is the mating system of these species. N. longiflora and N. plumbaginifolia are both self-compatible, although the former does not usually self in nature. N. plumbaginifolia is highly autogamous so it does not rely upon pollinators for fertilization and may have been selected to economize on nectar rewards.

Species	primary pollinators	mating system
N. longiflora	hawkmoths	Self-compatible (SC), facultative outcrosser but at least one population selfs regularly in the glasshouse
N. plumbaginifolia	hawkmoths	SC, autogamous & cleistogamous
N. alata	hawkmoths	Self-incompatible (SI)-enforced outcrossing
N. langsdorfii	hummingbirds, Bombus, Halictids	SI-enforced outcrossing but some populations studied by Bruce McClure are SC.
N. forgetiana	hummingbirds, Halictid bees	SI-enforced outcrossing
N. mutabilis	hummingbirds, others?	SI-(new flrs white, older ones pink)
N. bonariensis	small perching moths	SI-enforced outcrossing
N. sp. novo ?	hummingbirds, Halictids and small moths	SI-enforced outcrossing

Comparisons to be made:

hawkmoth pollinated species (N. alata, N. longiflora, N. plumbaginifolia) versus (primarily) hummingbird-pollinated species (N. forgetiana, N. langsdorfii, N. mutabilis).
hawkmoth-pollinated and hummingbird-pollinated species versus perching moth-pollinated N.bonariensis.
Within hawkmoth-pollinated species, autogamous N. plumbaginifolia vs. self-compatible but not autogamous N. longiflora, vs. self-incompatible N. alata.

Nectar characteristics to be considered:

-Volume is highly variable depending upon conditions during growth, daily weather conditions, time of day, and age of flowers. This is the easiest characteristic to measure and can elucidate patterns in nectar secretion.
-Sugar concentration can be easily estimated using a refractometer. This characteristic is slightly susceptible to environmental conditions. Small variations can result from changes in weather conditions, and this should be considered while taking measurements. Sugar concentration indicates the viscosity of the nectar, the more viscous the nectar the more difficult the collection.
-Sugar composition is a relatively constant characteristic within species. Sugars can be separated through paper chromotography. Each sugar spot on the paper will fluoresce under UV illumination. Sugar spots can be cut out, washed off the paper and analyzed with a fluorometer.
-Amino acid concentration is weakly correlated with sugar concentration. Environmental conditions can have the same effect on both characteristics. Amino acid concentraion can be determined by staining a nectar spot with ninhydrin and scoring the depth of color produced against standards of known concentration.
-Amino acid composition is an extremely constant characteristic within species. Therefore, this trait could have great taxonomic significance. The consituents can be revealed through thin-layer chromotography. Good resolution requires 2-4 different solvents in a bidimensional frame. Individual spots can be detected with UV illumination and separated from the plate. Characteristic absorbance and emission spectra can be obtained though fluoro-spectroscopy.

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