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Butterfly evolution is the origin and diversification ofbutterflies through geologic time and over a large portion of the Earth's surface. The earliest known butterfly fossils are from the midEocene epoch, between 40-50 million years ago.[1][dubious –discuss] Their development is closely linked to the evolution of flowering plants, since both adult butterflies and caterpillars feed on flowering plants. Of the 220,000 species ofLepidoptera, about 45,000 species are butterflies, which probably evolved from moths. Butterflies are found throughout the world, except in Antarctica, and are especially numerous in the tropics; they fall into eight different families.
The butterflies form the cladeRhopalocera, which is composed of three superfamilies:Hedyloidea (the moth butterfly familyHedylidae), theHesperioidea (the skipper familyHesperiidae), and thePapilionoidea (the true butterfly familiesPapilionidae,Pieridae,Nymphalidae,Lycaenidae, andRiodinidae). All of these families aremonophyletic. The Hedyloidea is thesister group to the other two superfamilies. Within the Papilionoidea, Papilionidae is the sister group to the other families, and Pieridae is the sister group to (Nymphalidae+(Lycaenidae+Riodinidae)). Phylogenetic hypotheses within the Nymphalidae are still under discussion. Current research is concentrated on subfamilial and tribal relationships, especially in the Nymphalidae.
| Phylogenetic relationships of butterfly families[2] |
The modern study of butterflies' higher classification began with Ehrlich's phenetic use of hundreds of previously overlooked morphological characters in tabular form, across families and major groups.[3] Scoble (1995)[4] and others continued the search for new characters, but with their application tocladism. Larval characters are now commonly integrated with those from adult butterflies. The addition of molecular data has allowed researchers to resolve clades in many lineages.
Evidence is gleaned frompaleontology where some 50 butterflyfossils have been identified, frommorphology and the study ofhomologies, frommolecular genetics and comparativebiochemistry, from comparativeethology, and from present-day geographical distributions and ecology.Even though butterflies are among the most studied insects, new findings are coming to light almost every month, and the prospect of a stable butterfly classification based on strongly supportedclades is seemingly within reach.[citation needed]
Butterfly fossils have been well covered by Grimaldi & Engel (2005),[5] who point out their weakness in resolving the sister group of the Rhopalocera: butterflies of 45 Mya are much like their living counterparts. The first fossil was formed around 40-50 million years ago.
Some species in theSatyrinae use ferns as larval host plants, and it is not impossible that the butterflies could have originated before their present-day angiosperm plant hosts. Evidence from the historical diversification of fifteen butterfly groups that show an increase in the diversification rates that follow major host shifts.[6]
Some researchers theorize that butterflies most likely originated in theCretaceous period when the continents were arrayed differently from their present positions and with climates unlike those of today. That is when the majorangiosperm radiation took place. Thus, butterfly evolution must be studied throughout the elaboration and testing ofphylogenetichypotheses and through historicalzoogeography. Researchers who accept a Cretaceous origin for the butterflies generally favorvicariant zoogeographic hypothesis for how the major lineages of butterflies came to be distributed over the world, whereas those who favor a Tertiary age rely on dispersalist hypotheses (Lamas, 2008).
Mimicry,hybridization, andco-evolution with host plants have probably contributed tospeciation in the butterflies (Lamas, 2008).
