Does hardness make flower love less promiscuous? Effect of biomechanical floral traits on visitation rates and pollination assemblages

CÓRDOBA, S.; COCUCCI, A. A.

ARTHROPOD-PLANT INTERACTIONS

SPRINGER

Lugar: Berlin; Año: 2017

1872-8855

p { margin-bottom: 0.25cm; line-height: 120%; }Visitation rates andassemblage composition of pollinators have often been related toenvironmental, eco- logical and phenotypic variables. However, theinteraction between flowers and pollinators has not been evaluated ina biomechanical context. Floral rewards in keel flowers (Fabaceae,Faboideae) are concealed behind four joined petals, the keel-wingunit, and are accessible only if pol- linators open this unit byexerting force on it. Force needed to open the flower is expected toaffect the interaction with pollinators because pollinators mustinvest time and energy to open the keels. Consequently, plants withstiff flowers should be expected to experience diminished visitationfre- quency, particularly by weak visitors. To test this expecta-tion of diminished visitation rates and of assemblage com- positionbiased by pollinator strength, we measured the force needed to openthe keel flowers of five co-occurring legume species and, using acanonical correspondence analysis (CCA), we tested their associationwith pollinator visitation rates and assemblage composition. Weaddition- ally included a size flag variable in CCA to test theeffect of attractiveness on pollinator visits. There was noassociation between flower stiffness and visitation frequency.Accord- ing to the CCA, pollinator assemblage compositions wereassociated with the force needed to open the keel and not flag size.As a general pattern, weak flowers are pollinated by an unevenassemblage of weak bees while the stiffest lowers are pollinated byan even assemblage of large and strong bees. These results supportsthe idea that force has an effect in controlling pollinatorassemblage composition.