548: New animal species evolves via hybridization

New Scientist Breaking News - New animal species evolved in an instant:

A new species of insect may have arisen in an evolutionary eye-blink as a result of cross-species mating. The discovery suggests that hybridisation - well known to be an important force in producing new plant species - may also be widespread in animals. Until now, it had been assumed that new animal species almost always arise by gradually splitting off from an existing lineage.

The probable new species belongs to a group of flies known as fruit maggots – highly specialised fruit parasites in which each species infests its own particular plant species.

In 1997, Bruce McPheron and his colleagues at Pennsylvania State University in University Park, US, noticed a fruit maggot infestation on introduced Asian honeysuckle bushes in north-eastern Pennsylvania. Since the host plant had only been in North America for about 250 years, the researchers decided to investigate how it ended up with such specialised pests.

They found that, genetically, the honeysuckle maggots looked like the result of hybridisation between two fruit maggot pests of native species, the blueberry maggot and the snowberry maggot. For example, earlier studies had shown that each of the latter two species bore certain unique gene variants found in no other fruit maggot species - yet the honeysuckle maggots carried variants from both blueberry and snowberry maggots.