Table 1: Three models for how genetically based behavioral incompatibilities due to conflicting habitat avoidance can evolve during speciation-with-gene-flow that cause postzygotic isolation in hybrids (see Figures 13).

Model 1: intermediate null allele (o)
 Step 1: state in ancestral population for a habitat choice locus with a recessive null (o) allele also segregating as low a frequency polymorphism that confers no habitat preference.
 Step 2: new habitat becomes available and o/o genotypes from ancestral population shift and adapt to novel habitat.
 Step 3: new avoidance mutation to ancestral habitat ( ) arises and elevates to high frequency in primarily null allele initial genetic background of novel habitat population.
 Step 4: new avoidance mutation to novel habitat ( ) arises that confers even greater fidelity to ancestarl habitat than allele and elevates to high frequency in the ancestral habitat population.
 Step 5: behavioral inviability/sterility in hybrids when individuals move between novel and ancestral habitat and cross mate producing heterozygotes at habitat choice locus.

Model 2: epistasis between habitat preference and avoidance loci
 Step 1: initial state exists for ancestral habitat preference at habitat preference locus in ancestral population and initial state for novel habitat avoidance at habitat avoidance locus.
 Step 2: new habitat becomes available and new preference mutation for novel habitat ( ) arises and elevates to high frequency in novel habitat population.
 Step 3: new avoidance mutation to ancestral habitat ( ) arises at avoidance locus and elevates to high frequency in novel habitat population because negative effects of heterozygosity at avoidance locus are not expressed in genetic background at the preference locus in the novel habitat.
 Step 4: behavioral inviability/sterility in hybrids when individuals move between novel and ancestral habitat and cross mate producing heterozygotes at habitat avoidance locus in genetic background of hybrids at the preference locus.

Model 3: epistasis between ancestral and novel habitat loci with preference and avoidance alleles
 Step 1: initial state exists for ancestral habitat preference at ancestral habitat choice locus in ancestral population and initial state for novel habitat avoidance at novel habitat locus.
 Step 2: new habitat becomes available and new preference mutation for novel habitat ( arises at novel habitat choice locus and elevates to high frequency in novel habitat population.
 Step 3: new avoidance mutation to ancestral habitat ( ) arises at ancestral habitat choice locus and elevates to high frequency in genetic background at the novel habitat locus in the novel habitat population.
 Step 4: behavioral inviability/sterility in hybrids when individuals move between novel and ancestral habitat and cross mate producing heterozygotes at ancestral habitat locus in genetic background of hybrids at the novel habitat locus.