Hybrids giving rise to new animal species

Two animal species can interbreed and evolve into a new species by moving to a different habitat, US researchers have concluded after discovering a genetically distinct fruit fly in North America.

In a study led by Dietmar Schwarz of Pennsylvania State University, they found that two animal species can become one, as opposed to the more common mechanism in which a single species splits to form two, they report in tomorrow's issue of Nature, the weekly British scientific journal.

The formation of a new species through hybridisation is known to occur in plants, but researchers had previously doubted that the same phenomenon could happen in animals, because hybrid offspring are less likely to survive and reproduce than pure-breds.

The new fruit fly species had recently switched its food source to a non-native honeysuckle plant in the northeastern United States, the Lonicera, which is thought to have come to North America in the last 250 years from Asia.

The Lonicera attracted a variety of fruit fly species that cross-bred to create hybrids.

Schwarz's team found that an initial population of hybrids went on to become a species in its own right.