Call Us: US - +1 845 478 5244 | UK - +44 20 7193 7850 | AUS - +61 2 8005 4826

The independent assortment hypothesis

Dependent assortment hypothesis

The dependent assortment hypothesis predicts that phenotypes are linked to each other. For example, a purple-flowered plant would always have green seeds (but never yellow seeds).

Independent assortment hypothesis

Alternatively, flower color and seed color could be independently assorted, in which purple-flowered plants could have green or yellow seeds, and a white-flowered plant could also have green or yellow seeds. In other words, flower color is independent of seed color.

Mendel’s dihybrid crosses

To test these alternate hypotheses, Mendel used the same approach as he did in his monohybrid crosses, except this time he analyzed two phenotypes at the same time. For our example, we will analyze his results of flower and seed color. He began his experiment by conducting several controlled crosses of one plant with two known dominant alleles generating a pure line: homozygote purple-flowered (FF) and yellow-seeded (SS). Collectively this is represented as FFSS. He conducted another controlled cross of another plant with two known recessive alleles, ffss. 

The independent assortment hypothesis predicts that during meiosis, gametes can acquire any possible combination of alleles (e.g. FS, FsFsor fs). If this hypothesis were supported, Mendel expected to see all possible phenotype combination in the F2generation: purple-flowered/green-seeded, purpled-flowered/yellow-seeded, white-flowered/green-seeded, and white-flowered/yellow-seeded. Furthermore, based on this understanding of segregation and recombination of alleles based on his monohybrid crosses, he could predict the relative abundance of each phenotyp