Data for: Mapping the evolution of accurate Batesian mimicry of social wasps in hoverflies

Hoverflies (Diptera: Syrphidae) provide an excellent opportunity to study
the evolution of Batesian mimicry, where defenceless prey avoid predation
by evolving to resemble defended ‘model’ species. While some hoverflies
beautifully resemble their hymenopteran models, others seem to be poor
mimics or are apparently non-mimetic. The reasons for this variation are
still enigmatic despite decades of research. Here, we address this issue
by mapping social-wasp mimicry across the phylogeny of Holarctic
hoverflies. Using the ‘distance transform’ technique, we calculate an
objective measure of the abdominal pattern similarity between 167 hoverfly
species and a widespread putative model, the social wasp, Vespula
germanica. We find that good wasp mimicry has evolved several times, and
may have also been lost, leading to the presence of non-mimics deep within
clades of good mimics. Body size was positively correlated with similarity
to the model, supporting previous findings that smaller species are often
poorer mimics. Additionally, univoltine species were less accurate wasp
mimics than multivoltine and bivoltine species. Hence, variation in the
accuracy of Batesian mimics may reflect variation in the opportunity for
selection caused by differences in prey value or signal perception
(influenced by body size) and phenology or generation time (influenced by
voltinism).