Example 4: Recombination

Starting off with a first pairing:

Pairing 4.1: olivgreen cock x skyblue hen Genetic formula: Cock bl+ D/bl+ D Hen bl D+/bl D+ The gametes produced by the cock are: bl+ D The gametes produced by the hen are: bl D+ Punnet square: bl+ D bl D+ bl+ D/bl D+ Solution: darkgreen/blue type II As before you can interchange the cock and the hen.

Because the cock can only produce gametes with bl⁺ and D and the hen can only produce gametes with bl and D⁺ the only possible offspring is darkgreen/blue type II (bl⁺ D/bl D⁺).

But what kind of gametes will this darkgreen/blue type II produce? Since both genes lie on the same chromosome, you would expect from the explenation on meiosis that both genes stay linked:
darkgreen/blue type II = bl⁺ D/bl D⁺ produces the gametes:

bl+ D

bl D+

But the explenation of meiosis wasn't accurate enough in order not to complicate things from the beginning. During meiosis recombination can occur.

More on recombination here. We'll continue with Example 4 after this intermezzo.