THE sexual habits of wild sunflowers have resolved a century-old debate in evolutionary biology. The flowers have revealed that new species can indeed form when two species mate to produce hybrid offspring.
In fact, hybridisation causes such an explosion of genetic variation that sunflower hybrids become new species capable of invading novel ecological niches. That suggests hybridisation may be more important than genetic mutations in causing rapid, widespread evolutionary transitions.
Biologists agree the formation of new species, or speciation, is driven by two processes. In ecological selection new species form as plants or animals adapt to changing environments. And in…
