Data from: Attack risk for butterflies changes with eyespot number and size

Butterfly eyespots are known to function in predator deflection and
predator intimidation, but it is still unclear what factors cause eyespots
to serve one function over the other. Both functions have been
demonstrated in different species that varied in eyespot size, eyespot
number and wing size, leaving the contribution of each of these factors to
butterfly survival unclear. Here, we study how each of these factors
contributes to eyespot function by using paper butterfly models, where
each factor is varied in turn, and exposing these models to predation in
the field. We find that the presence of multiple, small eyespots results
in high predation, whereas single large eyespots (larger than 6 mm in
diameter) results in low predation. These data indicate that single large
eyespots intimidate predators, whereas multiple small eyespots produce a
conspicuous, but non-intimidating signal to predators. We propose that
eyespots may gain an intimidation function by increasing in size. Our
measurements of eyespot size in 255 nymphalid butterfly species show that
large eyespots are relatively rare and occur predominantly on ventral wing
surfaces. By mapping eyespot size on the phylogeny of the family
Nymphalidae, we show that these large eyespots, with a potential
intimidation function, are dispersed throughout multiple nymphalid
lineages, indicating that phylogeny is not a strong predictor of eyespot
size.