We integrate experimental studies attempting to duplicate all or part
of the speciation process under controlled laboratory conditions and a
sk what general conclusions can be made concerning the major models of
speciation. Strong support is found for the evolution of reproductive
isolation via pleiotropy and/or genetic hitchhiking with or without a
llopatry. Little or no support is found for the bottleneck and reinfor
cement models of speciation. We conclude that the role of geographical
separation in generating allopatry (i.e., zero gene flow induced by s
patial isolation) has been overemphasized in the past, whereas its rol
e in generating diminished gene flow in combination with strong, disco
ntinuous, and multifarious divergent selection, has been largely unapp
reciated.