Zygomorphic flowers have fewer potential pollinator species

Area of Science:

• Ecology
• Botany
• Evolutionary Biology

Background:

• Bilaterally symmetrical (zygomorphic) flowers are often associated with specialized pollination interactions compared to radially symmetrical (actinomorphic) flowers.
• Zygomorphic flowers can enhance pollinator precision and exclude less effective visitors, but empirical data on reduced pollinator diversity is limited.

Purpose of the Study:

• To evaluate whether zygomorphic flowers are visited by a smaller subset of available pollinator species globally and within local communities.
• To investigate the implications of reduced pollinator diversity for plant-pollinator network structure and extinction risk.

Main Methods:

• Compiled and analyzed 53,609 floral visitation records from 159 ecological communities.
• Classified plant floral symmetry as zygomorphic or actinomorphic.
• Analyzed plant-pollinator network structure, including connectance, asymmetry, and coextinction robustness.

Main Results:

• Plants with zygomorphic flowers were visited by significantly fewer pollinator species globally and within individual communities.
• Zygomorphic flowers exhibited higher sharing of visitor species with co-occurring plants, especially other zygomorphic species.
• Visitation sub-networks for zygomorphic species showed greater connectance and asymmetry, and lower coextinction robustness.

Conclusions:

• Reduced pollinator diversity associated with zygomorphic flowers may influence plant diversification.
• Species with zygomorphic flowers might face a higher risk of extinction due to pollinator loss, impacting ecosystem stability.