LABORATORY EXPERIMENTS ON SPECIATION - WHAT HAVE WE LEARNED IN 40 YEARS

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.