Final answer:
In the case of linked genes, parental genotypes are the most abundant in progeny due to genes being inherited together, while recombination events produce fewer nonparental genotypes.
Step-by-step explanation:
For linked genes, the most abundant genotype in the progeny are those that have the parental genotypes. These are the combinations of alleles that were originally present in the parents.
When two genes are situated close together on the same chromosome, they are considered to be linked and typically are inherited together during meiosis, leading to a higher frequency of progeny with the parental genotypes.
However, recombination or crossing-over can occur, which produces nonparental genotypes (recombinant types) at a lower frequency.
Thomas Hunt Morgan's work with fruit flies provided evidence for this phenomenon.
For instance, if we have a heterozygous parent with alleles AB and ab (where A and B are dominant alleles and a and b are their respective recessive alleles on the same chromosome), and this individual is test crossed with a homozygous recessive parent (aabb).
The majority of offspring would likely display the parental genotypes (AaBb and aabb), with fewer offspring showing the recombinant genotypes (Aabb or aaBb).