An x-linked gene produces spots on some platyfish. all platyfish have an autosomal repressor that inhibits the expression of the spot-producing gene. the closely related swordtail lacks both the spot-producing gene and the repressor. in backcrosses between these two species, some hybrids receive the spot-producing gene but not the repressor. these individuals can develop malignant tumors, because the expression of the spot-producing gene is not properly regulated. this appears to be an example

The correct answer is - The Dobzhansky-Muller Model.

Explanation:

The Dobzhansky- muller model is a model that explains about how the natural selection influences speciation or reproductive isolation in a specific process when hybridization takes place between 2 species of an organism.

The offspring that produce through this process is an incompatibility with other species of origin. In the given question, spotted platyfish that arise due to the X linked gene exhibits the Dobzhansky-muller model.

Thus, the correct answer is - The Dobzhansky-Muller Model.