Bateson–Dobzhansky–Muller model

The Bateson-Dobzhansky-Muller Model, also known as Dobzhansky-Muller Model, is a model of the evolution of genetic incompatibility, important in understanding the evolution of reproductive isolation during speciation and the role of natural selection in bringing it about. The theory was first described by William Bateson in 1909, then independently described by Theodosius Dobzhansky in 1934, and later elaborated in different forms by Herman Muller, H. Allen Orr and Sergey Gavrilets.

The model states that genetic incompatibility is most likely evolved by alternative fixation of two or more loci instead of just one, so that when hybridization occurs, it is the first time for some of the alleles to co-occur in the same individual. For example, imagine two populations that only recently separated geographically. Both sides are starting with the same genotype AABB. One population can then evolve to aaBB, through the transition state AaBB, while the other evolves to AAbb, through the transition state AABb. During these processes, a allele will co-occur with A and B alleles, and b will co-occur with A and B alleles, without fitness consequences. When hybridization occurs, it is the first time a and b alleles co-occur, and they are the alleles that are incompatible.

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