Ecological convergence in phytochemistry and flower-insect visitor interactions along an Andean elevation gradient

Area of Science:

• Ecology
• Evolutionary Biology
• Plant Biochemistry

Background:

• Plant specialized metabolites are thought to evolve in response to local environmental conditions.
• Closely related species in similar habitats may exhibit phylogenetic convergence or divergence in traits.
• Understanding these patterns is crucial for explaining biodiversity along ecological gradients.

Purpose of the Study:

• To investigate whether closely related *Haplopappus* species converge in floral odor production along Andean elevational gradients.
• To determine if biotic interactions, specifically pollination and seed predation, also converge within elevation bands.
• To link floral scent convergence with ecological outcomes of plant-insect interactions.

Main Methods:

• Untargeted analysis of floral volatile organic compounds (VOCs) in *Haplopappus* species across elevational bands.
• Insect olfactory bioassays to assess floral visitor preferences.
• Quantification of seed predation versus successful pollination to determine cost-benefit ratios.

Main Results:

• Floral odors clustered according to elevational bands, indicating scent convergence.
• The primary floral visitor showed a preference for low-elevation floral scents.
• The ratio of predated to fertilized seeds was consistent within elevation bands but increased with elevation (6:1 low, 8:1 high).

Conclusions:

• Climate and insect community shifts along elevation likely drove the convergence of floral odor blends.
• Phytochemical convergence influences plant-insect interactions and their ecological outcomes.
• Higher elevations incur greater per capita herbivory costs due to sparser plant populations and resources.