Structural anther mimics improve reproductive success through dishonest signaling that enhances both attraction and the morphological fit of pollinators with flowers.

Abstract

Numerous studies have identified traits associated with anther mimicry; however, the processes underlying floral deception remain poorly documented for these structures. We studied the importance of pollinator attraction and mechanical fit of anther mimics in Tritonia laxifolia (Iridaceae) and their relative contributions to reproductive success. To determine anther mimics role in attraction, we offered bees’ binary choices to flowers painted with UV‐absorbent and UV‐reflecting paints. We also conducted preference experiments between flowers with excised anther mimics and unmanipulated controls, from which mechanical fit was assessed by allowing single visits. Anther mimics’ effects on female reproductive success were determined using similar treatments, but on rooted plants. Bees preferred UV‐absorbent over UV‐reflecting anther mimics. Bees did not discriminate between flowers with and without three‐dimensional anther mimics. Single visits resulted in more pollen deposition on unmanipulated controls over flowers with their anther mimics excised, which was directly linked to pollen‐collecting behavior. Controls with unmanipulated anther mimics had higher seed set than those with their anther mimics excised. This study provides insights into pollinator‐mediated selection on deceptive floral signals and shows that three‐dimensional anther mimics increases reproductive success through both attraction and pollen‐collecting behaviors.