Sub-functionalization of dorsal and ventral eyes in a whirligig beetle (Coleoptera: Gyrinidae)

Abstract

Compound eyes in nocturnal or fossorial insects generally express visible light opsins at higher levels than diurnal insects. In this study, we tested whether dorsal (above water) and ventral eyes (below water) of the diurnal four-eyed whirligig beetle Gyretes sericeus Laboulbène, 1853, resemble opsin expression and function of diurnal or nocturnal insect eyes respectively. By immunocytochemistry, we compared expression of green LW-opsin in dorsal and ventral rhabdoms of whirligig beetle ommatidia. Basal rhabdomeres (bR) showed comparable expression levels of LW-opsin in both dorsal and ventral ommatidia. In contrast, the inner proximal (R1p) and distal (R1d) bR showed a weak and narrow expression dorsally, whereas R1p and R1d showed a higher and expanded expression ventrally. To test whether dorso-ventral specialization of ommatidia results in functional differences in light response, we studied the behavior of beetles after selective eye-occlusion experiments. During phototaxis experiments, whirligig beetles typically showed a clear preference for light. Positive phototaxis was mainly disrupted after dorsal eye occlusion suggesting dorsal dominance of light sensing. Together, differences in opsin expression, structure, and function of whirligig beetle eyes suggest dorso-ventral sub-functionalizations resembling eye adaptations of diurnal and nocturnal insects. We discuss how dorsal and ventral eye specializations may have evolved in adephagan beetles.

Retracted: A new aquatic beetle (Adephaga: Coptoclavidae) from the Middle Jurassic Daohugou Biota

“…nov. contrasting to the presence of four eyes (two dorsal eyes and two ventral eyes) in other reported coptoclavids (e.g., D. primitinus ; Hispanoclavina diazromerali Soriano, Ponomarenko & Martínez‐Delclòs, 2007; Hispanoclavina gratshevi Ponomarenko & Martínez‐Delclòs, 2007; Pseudohydrophilus avitus Deichmüeller, 1886). Two pair of eyes composed of the dorsal and ventral eyes are a typical feature of extant Whirligig beetles (Coleoptera: Gyrinidae), which is adapted for life in an air/water interphase with this exceptional eye conformation (Salamanca & Brown, 2018). Therefore, it can be inferred that T. baii , C. longipoda , and S. larissae live underwater like the extant Dytiscoidae, but contrary to the Gyrinidae, which is capable of diving and flying but spending most of their time on the water surface, half emerged (Blagodatski et al, 2014).…”

Functional Anatomy of Split Compound Eyes of the Whirligig Beetles Dineutus mellyi (Coleoptera: Gyrinidae)

“…Therefore, due to varying light parameters in air and water, the dorsal and ventral eyes are expected to exhibit different adaptations, including in their general anatomy [18,19] and nanostructures. Salamanca & Brown (2018) reported that the dorsal eyes of whirligig beetles Gyretes sericeus exhibit morphological similarities to the apposition compound eyes of the diurnal insects, while the ventral eyes showed similar morphological features to the superposition eyes of the nocturnal insects [20]. Atomic force microscope images revealed distinct nanostructures on the facets of the dorsal and ventral eyes in both genera Gyrinus and Orectochilus.…”

Da luz à escuridão: história evolutiva do sistema fotosensorial em planárias (Platyhelminthes, Tricladida)

“…simple pigmented epithelium connected with photoreceptor cells in platyhelminths; iii. morphofunctional variation of compound eyes of insects with intriguing visual capacities (Salamanca & Brown, 2018;Warrant, 2015); iv. camera eyes in vertebrates, cephalopods, arthropods, and polychaetas (Fernald, 2000;Land & Nilsson, 2012).…”