1. Coyne, J. A. & Orr, H. A. Speciation (Sinauer Associates, Sunderland, Massachusetts, 2004). This book is a rigorous, authoritative and provocative review of the entire field of speciation.
2. Darwin, C. R. On the Origin of Species by Means of Natural Selection, or the Preservation of Favoured Races in the Struggle for Life (John Murray, London, 1859).
3. Dobzhansky, T. Genetics and the Origin of Species (Columbia Univ. Press, New York, 1937).
4. Mayr, E. Systematics and the Origin of Species (Columbia Univ. Press, New York, 1942).
5. Howard, D. J. et al. The genetics of reproductive isolation: a retrospective and prospective look with comments on ground crickets. Am. Nat. 159, S8–S21 (2002).