Evolution: Butterfly ball
31 / 10 / 2013, Economist Science and Technology
Pinning down the truth
BIOLOGISTS love Heliconius. In the 19th century, the mimicry by edible butterflies and moths of the brash warning colours sported by members of this genus (Heliconius butterflies themselves are usually toxic) was one of the first-noted and best examples of natural selection at work. And the genus is still doing duty in evolutionary biologists’ laboratories. Marcus Kronforst of the University of Chicago, for example, is using it to understand how speciation happens.Despite its ambitious title, Charles Darwin’s master work did not really explain “the origin of species”. Rather, it explained how species change, which is not quite the same thing. For new species to originate, that change must bifurcate. This can happen if a population gets physically divided—perhaps by an alteration in the climate making parts of its range uninhabitable. But that does not seem enough to explain all the biodiversity seen today, which suggests that undivided populations speciate too. Dr Kronforst and his colleagues have been trying to work out how this happens, at least in...