Caterpillars evolved from onychophorans by hybridogenesis
PNAS 2009 AOP
I reject the Darwinian assumption that larvae and their adults evolved from a single common ancestor. Rather I posit that, in animals that metamorphose, the basic types of larvae originated as adults of different lineages, i.e., larvae were transferred when, through hybridization, their genomes were acquired by distantly related animals. “Caterpillars,” the name for eruciforms with thoracic and abdominal legs, are larvae of lepidopterans, hymenopterans, and mecopterans (scorpionflies). Grubs and maggots, including the larvae of beetles, bees, and flies, evolved from caterpillars by loss of legs. Caterpillar larval organs are dismantled and reconstructed in the pupal phase. Such indirect developmental patterns (metamorphoses) did not originate solely by accumulation of random mutations followed by natural selection; rather they are fully consistent with my concept of evolution by hybridogenesis. Members of the phylum Onychophora (velvet worms) are proposed as the evolutionary source of caterpillars and their grub or maggot descendants. I present a molecular biological research proposal to test my thesis. By my hypothesis 2 recognizable sets of genes are detectable in the genomes of all insects with caterpillar grub- or maggot-like larvae: (i) onychophoran genes that code for proteins determining larval morphology/physiology and (ii) sequentially expressed insect genes that code for adult proteins. The genomes of insects and other animals that, by contrast, entirely lack larvae comprise recognizable sets of genes from single animal common ancestors.This? In PNAS of all places?
Basically, worm hybridised with insect to make grub-like larval forms. Yeah. I thought "k, maybe the paper itself may have some data, or something", and even VPN'd to get it. It actually wasn't really worth it. At all. There was nothing of substance there .I expected some grotesquely misinterpreted data. It was disappointing: a few drawings pointing out the visual similarities (very robust methodology, especially for constructing phylogenetic trees. Absolutely failproof.), some rather sketchy-looking tree I was too lazy to figure out in the 2min I could spare for that paper. And discussiony-looking text. Kinda reminiscent of a certain creationist 'journal' we do not speak of in fear of death by laughter...
Via Musings of The Mad Biologist, wherein the paper is gently chewed up (could be worse). I really like the phrase 'clusterfuck of genes'. I'll be sure to steal it when necessary. Because that's really the only argument you need against this paper. And also, genes don't work like that. Really, they don't.
Come to think of it, neither does evolution. Or decent science.