Data from: Predation favours Bicyclus anynana butterflies with fewer forewing eyespots

There are fewer eyespots on the forewings versus hindwings of nymphalids but the reasons for this uneven distribution remain unclear. One possibility is, in many butterflies, the hindwing covers part of the ventral forewing at rest and there are fewer forewing sectors to display eyespots (covered eyespots are not continuously-visible and are less likely to be under positive selection). A second explanation is that having fewer forewing eyespots confers a selective advantage against predators. We analysed wing overlap at rest in 275 nymphalid species with eyespots and found that many have exposed forewing sectors without eyespots: i.e. wing overlap does not constrain the forewing from having more eyespots than the hindwing. We performed two predation experiments with mantids to compare the relative fitness of and attack damage patterns on two forms of Bicyclus anynana butterflies, both with seven hindwing eyespots, but with two (in wildtype) or four (in Spotty) ventral forewing eyespots. Spotty experienced more intense predation on the forewings, were shorter-lived and laid fewer eggs. These results suggest that forewing eyespot number in B. anynana is limited by predation pressure. This may occur if attacks on forewing eyespots have more detrimental consequences for flight than attacks on hindwing eyespots.Please find this information in the ReadMe file ("Chan_et_al_-_Readme.txt") and in the Proceedings B publication (https://doi.org/10.1098/rspb.2020.2840). Funding provided by: National Research Foundation SingaporeCrossref Funder Registry ID: http://dx.doi.org/10.13039/501100001381Award Number: Investigatorship Award, NRF-NRFI05-2019-0006Funding provided by: National Research Foundation SingaporeCrossref Funder Registry ID: http://dx.doi.org/10.13039/501100001381Award Number: Competitive Research Programme, NRF-CRP20-2017-0001Funding provided by: Ministry of Education - SingaporeCrossref Funder Registry ID: http://dx.doi.org/10.13039/501100001459Award Number: Singapore's Academic Research Fund, R-154-000-602-112Please find this information in the ReadMe file ("Chan_et_al_-_Readme.txt") and in the Proceedings B publication (https://doi.org/10.1098/rspb.2020.2840)