Extensive pollinator sharing does not promote character displacement in two orchid congeners

Area of Science:

• Ecology
• Evolutionary Biology
• Botany

Background:

• Pollinator sharing between related species can drive evolutionary divergence.
• Character displacement is expected to be more pronounced in sympatric populations where species interact.

Purpose of the Study:

• To test if pollinator sharing between two orchid congeners promotes species divergence.
• To investigate the costs and consequences of pollinator sharing in orchids.

Main Methods:

• Characterized floral traits and pollination niches in pure and mixed populations.
• Quantified pollen limitation and measured phenotypic selection on floral traits.
• Performed controlled crosses to assess reproductive success.

Main Results:

• Orchid species shared pollinators extensively despite divergent floral traits.
• Only scent emission timing diverged more in mixed sites, but pollinator visitation did not mirror this.
• No evidence of divergent selection on floral traits or increased pollen limitation in mixed populations.
• Interspecific crosses yielded high proportions of viable seeds.

Conclusions:

• Pollinator sharing between these orchid species does not promote significant character displacement.
• The costs associated with pollinator sharing appear to be low.
• Characterizing both floral traits and ecological niches is crucial for understanding character displacement.