Dynamic iridescent signals of male copperwing damselflies coupled with wing-clapping displays: the perspective of different receivers

Abstract

Dynamic signals are a widespread phenomenon in several taxa, usually associated with intraspecific communication. In contrast, dynamic iridescent signals are detectable only at specific angles of illumination; hence, the animal can hide the signal to avoid detection when necessary. This structural coloration is mostly dependent on the illumination, the contrast against the background and the vision of the receiver. Complex behavioural displays can be coupled with structural coloration to create dynamic visual signals that enhance these functions. Here, we address whether iridescence of the males of a damselfly that inhabits dark rainforests, Chalcopteryx scintillans, can be considered a dynamic visual signal. We analyse whether coloration is perceived by conspecifics, while reducing detectability to eavesdroppers against three types of backgrounds. Our results suggest that the visual background affects the detectability of male hindwings by different receivers, mostly predators and prey. We discuss whether these results and the angle dependence of colour could indicate a mechanism to avoid unwanted intraspecific interactions or even to lure both predators and prey. We conclude that the main functions of the dynamic iridescent signal are to communicate with conspecifics while hindering the signal for prey, adding evidence of the multifunctionality of structural coloration coupled with behavioural displays in animals.

Camouflage by counter‐brightness: the blue wings of Morpho dragonflies Zenithoptera lanei (Anisoptera: Libellulidae) match the water background

“…These results add to those reported for males of other odonates, Chalcopteryx scintillans (Cezário et al., 2021). Males of C .…”

“…These results add to those reported for males of other odonates, Chalcopteryx scintillans (Cezário et al, 2021). Males of C. scintillans have dark wings that keep the animal hidden in the dark Amazon rainforest.…”

“…scintillans have dark wings that keep the animal hidden in the dark Amazon rainforest. However, with a quick movement of the wings, males shine bright iridescent coppery wings when they want to signal their presence to females and rivals (Cezário et al., 2021; Guillermo‐Ferreira et al., 2014, 2019). Hence, the results we found here support our initial predictions that Z .…”

“…In other words, animals are usually able to control the brightness of such iridescent colours using body postures and spatiotemporal dynamics to increase or decrease detection (Hutton et al., 2015). Although several odonate species exhibit iridescent wings, ultraviolet (UV) reflecting nanostructures and complex behavioural displays, only one study shows evidence of a possible role of such dynamic colours for camouflage in odonates (Cezário et al., 2021).…”

“…If true, theory predicts that Z. lanei would match the visual properties (i.e., brightness or colour) of the habitat in which they are found when perceived by a predatory bird but also exhibit traits (e.g., behaviours) that would allow them to reduce their detectability (Stevens & Merilaita, 2009). Zenithoptera lanei dragonflies display wing claps, as mentioned above, which consist of a slow opening of the wings and a rapid closing movement (Bick & Bick, 1978;Guillermo-Ferreira, 2021), where the individual alternates the exposure of ventral and dorsal wing surfaces to create a dynamic, angle-dependent iridescent signal (Cezário et al, 2021;Guillermo-Ferreira et al, 2015). The bright wing colours may be undetectable or confusing, enabling Z. lanei to choose when and where to signal to conspecifics to avoid unwanted intraspecific interactions (see Hutton et al, 2015).…”