Differential effects of petal and anther damage on pollinator behavior and plant reproduction in an enantiostylous species

Abstract

Florivory can affect plant reproduction by altering pollinator behavior, especially in species with specialized floral structures. We investigated these effects using Senna aversiflora, an enantiostylous species susceptible to floral damage, as a species model. The objective of this study was to analyze the influence of floral damage on the frequency of pollinator visits and the quality of reproduction. We tested the following hypotheses: (a) flowers with damaged petals and anthers are less visited than flowers without damage; (b) healthy flowers have a higher fruit set than flowers with damaged petals and anthers; and (c) healthy flowers present higher quantitative aspects of fruits and seeds than damaged flowers. The study was carried out with ten individuals and three treatments (intact flowers, flowers with damaged petals and flowers with damaged anthers). We conducted focal observations of visitors to the flowers of each treatment. The flowers visited were monitored until fruiting, and the collected fruits were analyzed for size, weight, number, and weight of seeds per treatment. Intact flowers received more visits (43%) than flowers with damaged petals (30%) and damaged anthers (26%). Fruit set was similar between intact flowers (86%) and flowers with damaged petals (83%), but lower in flowers with damaged anthers (70%). However, the quality of fruits and seeds did not differ significantly between treatments. Florivory affected the frequency of visits, but did not influence the size of the fruits or the number and weight of the seeds, possibly due to the species capacity for reproductive compensation that allows the plants to produce fruits and seeds with unchanged characteristics despite the stress caused by florivory.