Abstract Detail

Ecology

Luizzi, Victoria [1], Petren, Hampus [2], Friberg, Magne [2].

Is Floral Scent Production Energetically Costly?

Flowers produce a variety of volatile organic compounds (scents) that have been shown to function in pollinator attraction and herbivore deterrence. It is often assumed that these volatiles are costly to produce, and costs are commonly invoked to explain observations such as the loss of fragrance associated with the transition to self-pollinating or the shutdown of scent production during times of low pollinator activity. However, while there is evidence for “ecological costs” of scent emission in the form of attraction of enemies such as herbivores, the existence of energetic production costs has yet to be convincingly demonstrated. We asked whether there is an energetic cost of producing floral volatiles using two experiments. First, we grew individuals of Alpine rock-cress (Arabis alpina, Brassicaceae) under different soil nutrient and water levels to investigate whether scent production would decrease under stressful abiotic conditions. Four individuals from each of 131 half-sibling families collected from 10 populations across Europe were divided among four treatments (high and low water availability and high and low nutrient availability in a 4 × 4 design) such that one representative of each family received each treatment. Floral scent was collected using dynamic headspace sampling and analyzed by gas chromatography-mass spectrometry. Second, we hand-pollinated the flowers of individuals in the two low-nutrient treatments and asked whether there was a tradeoff between scent production and reproduction, which would provide more direct evidence of a fitness cost of producing floral scent. While plants that received less water or nutrients had lower biomass and produced fewer flowers than plants grown under optimal conditions, we found no evidence of changes in per-flower scent emission caused by nutrient or water availability. In contrast, we did find a significant negative correlation between scent production and number of developed fruits. However, there was only a marginally significant negative correlation between scent production and seed number, suggesting that the tradeoff between scent and fruit production does not translate, or translates only weakly, to effects on total reproductive output. These results suggest that while there are tradeoffs between scent production and some reproductive measures, per-flower scent production is canalized: investment in other structures such as leaves and roots may be sacrificed under abiotic stress while floral scent is held constant.

1 - University of Arizona, Ecology and Evolutionary Biology, 1041 E Lowell St, Tucson, AZ, 85719, USA
2 - Lund University, Biology, Sölvegatan 37, Lund, 223 62, Sweden

Keywords:
Floral Scent
tradeoffs
cost.

Presentation Type: Poster
Session: P, Ecology Posters
Location: Arizona Ballroom/Starr Pass
Date: Monday, July 29th, 2019
Time: 5:30 PM This poster will be presented at 5:30 pm. The Poster Session runs from 5:30 pm to 7:00 pm. Posters with odd poster numbers are presented at 5:30 pm, and posters with even poster numbers are presented at 6:15 pm.
Number: PEC019
Abstract ID:686
Candidate for Awards:Ecological Section Best Graduate Student Poster