Mimicry promotes morphological diversification but not speciation in mimetic swallowtail butterflies

Abstract

AbstractSpecies and morphological diversity may be complementary but need not be linked. The evolution of sexual dimorphisms and polymorphisms may promote morphological diversification but not speciation. We tested this hypothesis inPapilioswallowtail butterflies (subgenusMenelaides) using a species-level molecular phylogeny, trait mapping, and diversification analyses. These butterflies show exceptional diversity in wing colour patterns with many sexually monomorphic, dimorphic, and polymorphic species. Ancestral trait mapping and trait evolution pathway analysis showed that non-mimetic monomorphism was ancestral, from which wing colour patterns had diversified following very few trait transitions among a large set of evolutionary paths. These evolutionary outcomes showed a degree of directional evolution from simpler sexually monomorphic wing patterns towards more complex sex-limited and sex-limited polymorphic mimicry, further enhancing morphological diversification. However, diversification analyses revealed that mimetic and non-mimetic clades had similar speciation and net diversification rates. Thus, mimicry has promoted morphological but not species diversification inPapilio, where the evolution of sexual dimorphism and polymorphism may have dampened the species diversification rates.