Floral scent evolution in the section Pseudophrys: pollinator-mediated selection or phylogenetic constraints?

Area of Science:

• Evolutionary biology
• Plant science
• Chemical ecology

Background:

• Mediterranean Ophrys orchids (section Pseudophrys) use specific floral scents for pollinator attraction.
• Understanding the evolution of these scents requires examining pollinator-mediated selection and phylogenetic constraints.

Purpose of the Study:

• Investigate the roles of pollinator-mediated selection and phylogenetic constraints in shaping floral scent evolution within Ophrys section Pseudophrys.
• Analyze floral scent composition in relation to phylogenetic relationships and pollination interactions.

Main Methods:

• Constructed a phylogenetic tree for 19 Pseudophrys species using three nuclear loci.
• Compiled pollination interaction data from literature and field observations.
• Analyzed floral scents using solid phase microextraction and gas chromatography-mass spectrometry.

Main Results:

• Confirmed the monophyly of section Pseudophrys and identified three main clades.
• Floral scent composition is influenced by both phylogenetic relationships and pollination interactions.
• Fatty acid esters showed a significant phylogenetic signal, while alkenes and alkadienes created dissimilarities between closely related species with different pollinators.

Conclusions:

• Floral scents in Ophrys Pseudophrys are shaped by a combination of pollinator-mediated selection and phylogenetic constraints.
• The relative influence of these forces varies across different classes of scent compounds.
• Distinct selective pressures on behaviorally active and inactive compounds likely contribute to these differences.