A non-evolutionary explanation has been found for a classic evolutionary showpiece: mimicry in butterflies.
Heliconius butterflies are well-known for having nearly identical wing patterns between species. Prior evolutionary explanations involved developing these patterns independently through mutation and natural selection. Now, a new paper in Nature shows that the butterflies share the genes for the patterns through hybridization.1
PhysOrg summarized the surprising findings:
The genetic sharing between species, researchers believe, is the result of hybridization. Considered extremely rare, particularly in animals, hybridization occurs when insects of two different species interbreed in the wild.
The resulting hybrid offspring share traits with both mother and father. Though often considered evolutionary dead-end, hybrids occasionally interbreed with a parent species, in the process introducing new genes that can help populations adapt to new or changing environments.
And what does this mean for Darwinian evolution?
“What we show is that one butterfly species can gain its protective colour pattern genes ready-made from a different species by hybridizing (or interbreeding) with it – a much faster process than having to evolve one’s colour patterns from scratch,” said Kanchon Dasmahapatra, a postdoctoral researcher at the University College of London’s Department of Genetics, Evolution, and Environment, and a co-author of the paper.
“This project really changes how we think about adaptation in general,” said Marcus Kronforst, a Bauer Fellow at Harvard, who participated in the sequencing. “Evolutionary biologists often wonder whether different species use the same genes to generate similar traits, like the mimetic wing patterns of Heliconius butterflies. This study shows us that sometimes different species not only use the same genes, but the exact same stretches of DNA, which they pass around by hybridization.”
The Nature paper had nothing to say about mutation and natural selection. Instead, as these excerpts show, it described the adaptation spreading by sharing genes (called introgression), not neo-Darwinism:
These patterns would be very hard to explain in terms of convergent functional-site evolution or random coalescent fluctuations. Instead, our results imply that derived colour-pattern elements have introgressed recently between both rayed and postman forms of H. timareta and H. melpomene.…
We have demonstrated repeated exchange of large (~100-kb) adaptive regions among multiple species in a recent radiation.…
Although it was long suspected that introgression might be important in evolutionary radiations, our results from the most diverse terrestrial biome on the planet suggest that adaptive introgression is more pervasive than previously realized.
This leaves an obvious question: How did the first butterfly evolve the ready-made pattern from scratch?
1. The Heliconius Genome Consortium, “Butterfly genome reveals promiscuous exchange of mimicry adaptations among species,” Nature (published online 16 May 2012), doi:10.1038/nature11041.
Sharing by hybridization is not neo-Darwinian evolution. How many textbooks have used butterfly mimicry as an example of Darwin in action? Now, scientists have to consider that the genes for these color patterns were already there, “ready made.” We learn that butterflies have the ability to swap & share pre-existing genetic information. This begs the question of where the information came from in the first place.
Darwinists might counter that the process aids survival of the fittest. OK, so what? That still doesn’t answer the question of the origin of the information. That evidence fits just as well, if not better, with the argument that intelligent design permits adaptation by mechanisms that allow sharing of beneficial genetic information. It’s a robust design feature, not an evolutionary innovation.
Notice that the scientists confessed that they long suspected that introgression could be important in “evolutionary radiations,” because it was hard to believe that “convergent evolution” could generate these patterns “from scratch.” But if it’s not evolution by neo-Darwinian means, it’s not an evolutionary radiation, and it’s not convergent evolution either. It’s design all the way around.
Notice also that they said these hybridization events occurred recently. They didn’t say how recent, but obviously, hybridization can occur in one generation. Presto: instant information in the genome, “ready made” for better survival.
We can’t let a butterfly story pass without a reminder that you can see Heliconius butterflies, and many other beautiful species, in Illustra’s latest ID masterpiece, Metamorphosis, available at metamorphosisthefilm.com.