Show Me The Science Month Day 21

Why do certain species of fruit flies prefer some fruits over others? Two biologists have looked at the genetic basis behind the evolution of fruit preference, in
a paper in this month's issue of
Genetics (an incredible issue which happens to contain another amazing, pioneering, paradigm-shifting,
ground-breaking paper).
Many insects specialize in feeding on just one or a few types of plants. This fact isn't that surprising, since plants have all sorts of defenses for warding off insects, including the production of toxic chemical compounds, and insects that feed on plants have typically evolved ways to get around the defenses of one type of plant, but not another. This phenomenon is dramatically played out in the hundreds of species of fruit flies around the world, many of which specialize in just one or a few types of fruit. Researchers at Michigan State and UNC Chapel Hill have looked at the genetic changes that enabled one species of fruit fly to specialize in the fruit of the Morinda plant, also known as cheese fruit, a fruit that is toxic to other flies.
Morinda citrifolia, photograph by Eric Guinther