Just now I remembered a theory that I'd read somewhere a few years back.. that the caterpillar and the butterfly were once two separate insects, and somehow the two genomes mixed... (by virus? or microRNA? or endosymbiosis? or mimicry?) I had a quick search and discovered this blog article from BugTracks:
"modern metamorphosing insects arose when velvet worms (phylum Onychophora) somehow hybridized with primitive arthropods"read more: http://bugtracks.wordpress.com/2011/11/22/lynn-margulis/
"she somehow intuited that I would one day become obsessed with gall-making insects, and she showed me a chapter in a book she had edited in which it was hypothesized that fleshy fruits arose when gall-making insects happened to induce galls in the reproductive tissues of plants, so that the genetic coding for gallmaking was incorporated into the plant’s heritable genome."
and this paper: Caterpillars evolved from onychophorans by hybridogenesis
and this response: Caterpillars did not evolve from onychophorans by hybridogenesis
Lynn Margulis died of a stroke, 22 November, 2011.
Other interesting effects are Mimicry, Mimetism, Camouflage etc... changes forced through environmental pressures. ...
[Parthenogenesis - Hybridogenesis]