Both Palatable and Unpalatable Butterflies Use Bright Colors to Signal Difficulty of Capture to Predators

Wilts

et al. 2020

Ecology and Evolution

Butterflies have evolved a diversity of color patterns, but the ecological functions for most of these patterns are still poorly understood. The Banded Swallowtail butterfly, Papilio demolion demolion, is a mostly black butterfly with a greenish‐blue band that traverses the wings. The function of this wing pattern remains unknown. Here, we examined the morphology of black and green‐blue colored scales, and how the color and banding pattern affects predation risk in the wild. The protective benefits of the transversal band and of its green‐blue color were tested via the use of paper model replicas of the Banded Swallowtail with variations in band shape and band color in a full factorial design. A variant model where the continuous transversal green‐blue band was shifted and made discontinuous tested the protective benefit of the transversal band, while grayscale variants of the wildtype and distorted band models assessed the protective benefit of the green‐blue color. Paper models of the variants and the wildtype were placed simultaneously in the field with live baits. Wildtype models were the least preyed upon compared with all other variants, while gray models with distorted bands suffered the greatest predation. The color and the continuous band of the Banded Swallowtail hence confer antipredator qualities. We propose that the shape of the band hinders detection of the butterfly's true shape through coincident disruptive coloration; while the green color of the band prevents detection of the butterfly from its background via differential blending. Differential blending is aided by the green‐blue color being due to pigments rather than via structural coloration. Both green and black scales have identical structures, and the scales follow the Bauplan of pigmented scales documented in other Papilio butterflies.

Section: Discussionmentioning

confidence: 99%

What's in a band? The function of the color and banding pattern of the Banded Swallowtail

Wilts

et al. 2020

Ecology and Evolution

“…Optimal foraging theory predicts that predators should avoid prey with increased handling times, especially when prey with lower handling times are abundant alternatives (Charnov, 1976;Krebs et al, 1977). Studies suggest that predators can learn to avoid unprofitable prey that are difficult to capture (Hancox & Allen, 1991;Pinheiro, 1996;Pinheiro et al, 2016), hard to process (Wang et al, 2018) or require long handling time (Cyriac & Kodandaramaiah, in press) when such prey possess conspicuous colours, even if the prey are non-toxic and palatable (Mappes, Marples & Endler, 2005). We here postulate that bright colours in uropeltid snakes reduce predation, possibly by signaling long handling times associated with attack deflection to the tails.…”

Section: Introductionmentioning

confidence: 99%

Peer Review #1 of "Conspicuous colours reduce predation rates in fossorial uropeltid snakes (v0.1)"

Rößler¹

2019

Uropeltid snakes (Family Uropeltidae) are non-venomous, fossorial snakes that are found above ground occasionally, during which time they are exposed to predation. Many species are brightly coloured, mostly on the ventral surface, but these colours are expected to have no function below the ground. Observations have shown that the cephalic resemblance (resemblance to heads) of uropeltid tails may direct attacks of predators towards the hardened tails, thereby potentially increasing handling times for predators. Experiments have also shown that predators learn to avoid prey that are nontoxic and palatable but are difficult to capture, hard to process or require long handling time when such prey advertise their unprofitability through conspicuous colours. We here postulate that uropeltid snakes use their bright colours to signal long handling times associated with attack deflection to the tails, thereby securing reduced predation from predators that can learn to associate colour with handling time. Captive chicken experiments with dough models mimicking uropeltids indicate that attacks were more common on the tail than on the head. Field experiments with uropeltid clay models show that the conspicuous colours of these snakes decrease predation rates compared to cryptic models, but a novel conspicuous colour did not confer such a benefit. Overall, our experiments provide support for our hypothesis that the conspicuous colours of these snakes reduce predation, possibly because these colours advertise unprofitability due to long handling times.

“…Biomimicking the structural iridescent colors of living organisms such as buttery wings, which may provide an important channel for mate signaling and communication as well as survival in hostile environments, is currently in the research limelight due to their fundamental importance and potential technological applications. [1][2][3][4][5][6] It has been demonstrated that the fascinating structural coloration in the wings of morpho butteries arises from the combination of highly ordered or quasi-amorphous structures and embedded black melanin, 7-10 with the periodic lattice structures generating the iridescent structural colors while the melanin enhances the color visibility by serving as a background absorber. 11,12 A variety of colloidal photonic crystals have been fabricated through facile self-assembly of different colloidal nanoparticles, such as silica, polystyrene, and poly(methyl methacrylate) into a close-packed array.…”

Section: Introductionmentioning

confidence: 99%

Biomimetic colloidal photonic crystals by coassembly of polystyrene nanoparticles and graphene quantum dots

et al. 2018