Data from: Detectability of a poison frog and its Batesian mimic depends on body posture and viewing angle

Aposematic signals warn predators that prey should be avoided due to
dangerous secondary defences. However, as warning signals do not always
produce avoidance, warning colours may evolve as a trade-off balancing
detectability against signal saliency. For Batesian mimics, which display
salient signals but lack secondary defences, the costs of predator
encounters are greater, potentially increasing the benefit of crypsis.
This raises the question of whether imperfect mimicry may reduce
detectability while retaining mimetic efficacy. We tested this hypothesis
with the poisonous frog Ameerega bilinguis and undefended Batesian mimic
Allobates zaparo, using computational visual modelling and screen-based
detection trials with human participants. We found that both species
incorporate camouflage into their warning colours, but to different
degrees depending on viewing angle and behaviour. Contrary to expectation,
we found differences in detectability between model and mimic that do not
adhere to the hypothesized cryptic mimetic phenotype. To aerial observers,
we found the mimic to be more detectable than the model. To terrestrial
observers, likely owing to the model’s bright ventral colour, we found the
model more detectable in viewing angles that highlight the ventral
colouration, while the mimic was more detectable in viewing angles that
highlight the dorsal colouration. Consequently, we suggest that in
addition to being the result of perceptual or developmental constraints,
imperfect mimicry may also evolve as an adaptive strategy which balances
camouflage with different signalling functions. Our findings complement
the emerging view that aposematic signals may evolve in response to a
multitude of selection pressures beyond aversion alone.