In the fruit fly Drosophila, a rudimentary wing called 'vestigial' and dark body color called 'ebony' are inherited as independently assorting genes and are recessive to their dominant counterparts full wing and gray body color. Dihybrid dominant-phenotype males and females are crossed, and 3200 progeny are produced. How many progeny flies are expected to be found in each phenotypic class?

Key Concepts

Independent Assortment

Independent assortment is a fundamental principle of genetics that states genes for different traits are inherited independently of one another. This means that the inheritance of one trait does not affect the inheritance of another, allowing for a variety of combinations in offspring. In the context of the question, the vestigial wing and ebony body color traits are inherited independently, which is crucial for predicting the phenotypic ratios of the progeny.

Dihybrid Cross

A dihybrid cross involves two traits, each represented by two alleles, allowing for the examination of how these traits segregate and assort during gamete formation. In this scenario, the traits are wing shape (vestigial vs. full) and body color (ebony vs. gray). The expected phenotypic ratio from a dihybrid cross of two heterozygous parents is typically 9:3:3:1, which helps in calculating the expected number of progeny in each phenotypic class.

Phenotypic Ratio

The phenotypic ratio is the ratio of different phenotypes that appear in the offspring from a genetic cross. In a dihybrid cross, the phenotypic ratio for two traits is often 9:3:3:1, representing the combinations of dominant and recessive traits. Understanding this ratio is essential for predicting how many progeny will exhibit each phenotype, which is necessary for answering the question regarding the expected number of progeny flies in each phenotypic class.