Non-genetic maggot speciation

Changes in aromatic preferences can cause "sympatric speciation" among maggots — a form of speciation that is not really genetic (the two species can still interbreed), but rather circumstantial: genetic differences contained in each species causes it to behave in a way that ensures it will never get it on with the other species.

The apple and hawthorn maggots are common names for the same species, Rhagoletis pomonella . The pest and the hawthorn plant are native to North America, but the apples they now infest were introduced from Europe around 250 years ago. During the 1860s, in New York's Champlain Valley, some hawthorn flies shifted to apple plants as their host, while others did not."There are no morphological differences between the two, so they are still the same species, but two races can be distinguished by looking at the diversity of protein structures of whole populations and by the specificity of individual flies to different host plants," explained Roelofs, who is the Liberty Hyde Bailey Professor of Insect Biochemistry at Cornell.

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