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.

Pollen, anther, stamen, and androecium mimicry

“…Other functions include guiding pollinators to a place for landing on a flower (Lunau 1996b), guiding pollinators to distinct locations after landing on a flower (Dinkel & Lunau 2001) including nectar holders, distracting pollinators from real stamens (Lunau 2007), increasing the visual similarity between flower morphs and flowering phases (Pohl et al 2008), and facilitating contact with pollen and stigmas through physical manipulation of the pollinators' position, as in Tritonia securigera (Fig. 7E; Newman et al 2022). A double function as signal and mechanical fit to pollinating bees has been shown for the staminode of Jacaranda rugosa (de Souza Pontes et al 2022).…”

“…7E; Newman et al . 2022). A double function as signal and mechanical fit to pollinating bees has been shown for the staminode of Jacaranda rugosa (de Souza Pontes et al .…”