Question

With Dobzhansky/Muller incompatibilities each population get's their own unique mutations. For the unique mutations to form what has to happen to the populations first.

  reproductive isolation

  the gene flow must stop

  the populations must be under strong selection

  both reproductive isolation and the gene flow must stop

  none of the other answer are correct

Answer 1

Reproductive Isolation must occur as the first step for new and unique mutations to occur. Dobzhansky–Muller model, is a model of the evolution of genetic incompatibility that helps us understand the evolution of reproductive isolation during speciation and the role of natural selection in it. This occurs because there are several ways that speciation occurs in the natural world, one of which is that a common ancestor can break off into many lineages due to reproductive isolations of certain populations or parts of populations of that species. The genetic makeup of those lineages changes over time through mutations and natural selection choosing the most favorable adaptations for survival. Once the species have diverged, many times they are no longer compatible and can no longer sexually reproduce with each other.

This explains how new alleles arise and are passed down in the newly formed species. Theoretically, an individual that would have a mutation at the chromosomal level would not be able to reproduce with any other individual. The model explains how a brand new lineage can arise if there is only one individual with that mutation; in their model, a new allele arises and becomes fixed at one point. In the other now diverged lineage, a different allele arises at a different point on the gene. The two diverged species are now incompatible with each other because they have two alleles that have never been together in the same population.

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