Gavrilets, S. 1997. ``Single locus clines'' Evolution 51 : 979-983


Bazykin (1969) found the form of a single locus cline arising from viability selection against heterozygotes when two populations, initially fixed for alternative alleles, come into contact in a continuous one-dimensional habitat. Here I have generalized Bazykin's results for the case of postmating reproductive isolation in the form of fertility selection as well as premating reproductive isolation.