Sibling species

pair of closely related species that are difficult to distinguish

Sibling species are species which look alike, but cannot breed with each other.[1][2][3]

The classic case is Drosophila pseudoobscura and D. persimilis. They are almost identical, but if flies from one species are put with flies from the other species, they do not interbreed. Another example was the European mosquito known as Anopheles maculipennis. This turned out to be a cluster of six different species, some of which transmit malaria, and some do not.[2]


  1. Ridley M. 1996. Evolution. 2nd ed, Blackwell Wiley. p404
  2. 2.0 2.1 Futuyma D.J. 2005. Evolution. Sinauer. p356
  3. Lincoln R.J; G.A. Boxshall and P.F. Clark 1982. A dictionary of ecology, evolution and systematics. Cambridge University Press. p227 ISBN 0-521-23957-5