Crosses Involving three or more pairs of genes

Example Problem

In Drosophila the following wild type alleles are used for analysis v (vermilion eyes), cv (cross-veinless) and ct (cut or snipped wing edges). Flies doubly recessive and homozygous (v+v+,cvcv,ctct) are crossed with flies singly recessive and homozygous (v v, cv+cv+, ct+ct+). Female progeny that are vv+, cvcv+, ctct+ are then test crossed with the tripley recessive males (v v, cv cv, ct ct)

Trihybrid cross Assuming Independent Assortment

There are two possible solutions

• Classical Solution
• Simplify and Solve

by Kenneth G. Wilson,
Professor of Botany
Miami University
wilsonkg@muohio.edu