Butterflies Show Origin of Species as an Evolutionary Process, Not a Single Event

The evolution of new species might not be as hard as it seems, even when diverging populations remain in contact and continue to produce offspring. That's the conclusion of studies, reported in the Cell Press journal Cell Reports on October 31st, that examine the full genome sequences of 32 Heliconius butterflies from the Central American rain forest, representing five different species.

"The butterflies have performed a beautiful natural experiment for us that lets us address important questions about evolution," said Marcus Kronforst of the University of Chicago. "Even as biologists, we often think of the origin of new species as a moment in time when a new species splits from an old one, and this type of thinking is reflected in the evolutionary 'trees,' or phylogenies, that we draw. In reality, evolution is a long-term process that plays out in stages, and speciation is no different."
Kronforst and his colleagues found that the initial divergence between butterfly populations is restricted to a small fraction of the genome. In the case of the butterflies, the key genes are those involved in wing patterning. The butterfly species under study all have very different wing patterns, which are important in the butterflies' mating behavior and predator avoidance.

http://www.sciencedaily.com/releases/2013/10/131031124914.htm