When opposites don’t attract
By Susan Milius
The quirks of two kinds of European corn borers are giving researchers another way to study how a single species might split in two.
The classic scenario for forming a new species starts when a geographic barrier, such as a mountain range, emerges and divides a single species.
In recent decades, though, biologists have found populations that seem to be splitting even though they could in theory mingle geographically. For instance, two races within a corn borer species in France live side by side but generally attack different host plants, says Thibaut Malausa of Paul Sabatier University-Toulouse III in France. One race feeds and lays eggs mostly on corn, while the other prefers hops or mugwort.