Nectar metabolomes contribute to pollination syndromes

Area of Science:

• Plant Biology
• Chemical Ecology
• Evolutionary Biology

Background:

• Pollination syndromes link floral traits to pollinator groups.
• Floral rewards, like nectar, may also be shaped by pollinator selection.
• The concept of a 'chemical pollination syndrome' is proposed.

Purpose of the Study:

• To investigate if nectar chemistry converges across different pollinator groups.
• To test the 'chemical pollination syndrome' hypothesis.
• To compare nectar and leaf chemical profiles in Salvia species.

Main Methods:

• Untargeted metabolomics was used to analyze nectar and leaf chemistry.
• 19 Salvia species, representing bee and bird pollination syndromes, were studied.
• Metabolite profiles were compared between nectar and leaf tissues and across pollination syndromes.

Main Results:

• Bird-syndrome nectar exhibited convergence in chemical traits, distinct from bee-syndrome nectar.
• Alkaloid composition and concentration were key drivers of nectar chemical differences.
• Nectar and leaf metabolomes were decoupled, and not strongly linked to phylogeny within Salvia.

Conclusions:

• Functional pollinator groups appear to drive the evolution of floral reward chemistry.
• Evidence supports the 'chemical pollination syndrome' hypothesis, indicating pollinator selection on nectar.
• Nectar chemistry is decoupled from other plant tissue chemistry.