Abstract Detail

Reproductive Processes

Muchhala, Nathan [1], Domingos-Melo, Arthur [2], Albuquerque-Lima, Sinzinando [2], Bezerra, Alexsandro [2], Frazão, Annelise [3], Johanes, Isabella [2], Sabino, Ana Carolina [2], Machado, Isabel Cristina [2].

Actinomorphy to zygomorphy: Bilateral symmetry, with correct flower orientation, greatly increases pollen transfer.

While the ancestral symmetry of angiosperm flowers is actinomorphic (radial symmetry), hundreds of lineages have independently evolved zygomorphic flowers (bilateral symmetry). Such shifts are associated with more specialized pollination systems, and lead to significant increases in diversification rates. But what are the actual benefits of zygomorphic flowers for a plant? One little-tested assumption is that zygomorphy maximizes pollen transfer by allowing flowers to place pollen in a more precise and repeatable way on pollinator’s bodies. This is supported by the fact that floral orientation tends to be more consistent, and often can be quickly readjusted, for zygomorphic flowers compared to actinomorphic ones. In this study, we performed flight cage experiments with nectar-feeding bats and artificial flowers, testing how floral symmetry and orientation affect pollen removal and transfer. For each flower, four anthers were placed either all of the way around the opening (actinomorphic) or together at one side of the opening (zygomorphic). Nearly twice as much pollen was transferred between zygomorphic flowers, but only when angled at 45°, causing pollen to be consistently placed on the tops of bats’ heads. When flowers were positioned flat (i.e. facing upwards), bats approached from many different angles, and zygomorphic flowers performed no better than actinomorphic ones in terms of pollen transfer. Thus, results suggest that shifts to zygomorphy allow more specialized pollination systems which, with the correct floral orientation, maximize pollen transfer success.

1 - University Of Missouri - St. Louis, Biology Dept., R223 Research Hall, One University Blvd, One University Blvd, St. Louis, MO, 63121, United States
2 - Universidade Federal de Pernambuco, Departamento de Botanica, Recife, Brazil
3 - Universidade de São Paulo, Departamento de Botânica, São Paulo, Brazil

Keywords:
Pollination
Floral morphology
Glossophaga soricina
Catimbau
Pollen transfer
Zygomorphy.

Presentation Type: Oral Paper
Number: RP4003
Abstract ID:848
Candidate for Awards:None