Irvine, CA, USA. Scientists now have their first look into how mimicry and convergent evolution happen at a genetic level, identifying a single gene responsible for color patterns in a variety of butterfly species.

For 150 years scientists have been trying to explain convergent evolution, how unrelated species can acquire the same biological traits while preserving their substantive differences.


The science team discovered that the same gene controls the evolution of red color patterns across remotely related butterflies.

The finding aligns with emerging evidence from various animal species that evolution generally is governed by a relatively small number of genes.

They concluded that out of the tens of thousands in a typical genome, it seems that only a handful tend to drive major evolutionary change over and over again.One of the best-known examples of this is how poisonous butterflies from different species evolve to mimic each other's color patterns – in effect joining forces to warn predators, Don't eat us, while spreading the cost of this lesson.

An international team of researchers led by Robert Reed, UC Irvine assistant professor of ecology & evolutionary biology, solved part of the mystery by identifying a single gene called optix responsible for red wing color patterns in a wide variety of passion vine butterfly species. The finding, which follows 10 years of work, appears in the journal Science.

The scientists spent several years crossbreeding and raising delicate passion vine butterflies in large netted enclosures in the tropics so they could map the genes controlling color pattern. UCI postdoctoral researcher Riccardo Papa then perfected a way to analyze the genome map by looking at gene expression in microdissected butterfly wings.

Finding a strong correlation between red color patterns and gene expression in one small region of the genome was the breakthrough that led to discovery of the gene.

Studies of population genetics in hybrid zones, where different color types of the same species naturally interbreed, confirmed the discovery.

"Biologists have been asking themselves, 'Are there really so few genes that govern evolution?'" Reed said. "This is a beautiful example of how a single gene can control the evolution of complex patterns in nature. Now we want to understand why: What is it about this one gene in particular that makes it so good at driving rapid evolution?"

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