Meet the hawthorn fly, also known as the apple maggot fly:
It is a remarkable case of speciation, as it was not developed in a laboratory, but by nature. In the nineteenth century, after apples were introduced in North America, a distinct "race" of hawthorn flies began feeding on them exclusively, even though they usually ate hawthorns. In this new race, called apple maggot flies, six out of thirteen allozyme loci are different than the original hawthorn-eating flies, hawthorn flies mature later in the season and take longer to mature than apple flies and there is little evidence of interbreeding (researchers have documented a 4-6% hybridization rate). This suggests that apple flies are evolution in progress.
- McPheron, B.A., Smith, D.C., Berlocher, S.H. (1988). "Genetic differentiation between host races of Rhagoletis pomonella". Nature. 336: 64-6.
- Feder, J.L., Chilcote, C.A., Bush, G.L. (1988). "Genetic differentiation between sympatric host races of the apple maggot fly, Rhagoletis pomonella." Nature. 336: 61-4.
- Smith, D.C. (1988). "Heritable divergence of Rhagoletis pomonella host races by seasonal asynchrony." Nature. 336: 66-7.
While studying the genetics of the evening primrose, Oenothera lamarckiana, botanist and geneticist Hugo de Vries found an unusual variant among his plants. O. lamarckiana has a chromosome number of 2N = 14. The variant had a chromosome number of 2N = 28. He found that he was unable to breed this variant with O. lamarckiana. He named this new species Oenothera gigas.
- de Vries, H. (1905). "Species and varieties, their origin by mutation."
L. Digby crossed the primrose species Primula verticillata and P. floribunda to produce a sterile hybrid. Polyploidization occurred in a few of these plants to produce fertile offspring. The new species was named P. kewensis.
- Digby, L. 1912. "The cytology of Primula kewensis and of other related Primula hybrids." Ann. Bot. 26: 357-88.