Final answer:
A recombination frequency of 0 indicates perfect linkage of genes on the same chromosome, with no recombinant offspring produced as these genes are inherited together and do not assort independently according to Mendel's law.
Step-by-step explanation:
The most likely explanation for having a recombination frequency of 0 is that the genes in question are perfectly linked, meaning they are located very close together on the same chromosome and do not separate during meiotic crossover events. According to Sturtevant's gene mapping approach, a recombination frequency of 0 implies that all offspring will inherit the alleles together, with no new allele combinations created through recombination. Therefore, these genes do not follow Mendel's law of independent assortment, which states that alleles for different traits are inherited independently of one another.
When alleles are far apart on a chromosome, or on separate chromosomes, chromosomal crossover can occur, which leads to a higher recombination frequency—up to 0.5, where there is an equal chance of parental and recombinant offspring. The closer the recombination frequency is to 0.5, the less certain it is if the genes are far apart on the same chromosome or on different chromosomes. Sturtevant represented these genetic correlations using map units or centimorgans (cM), where a recombination frequency of 0.01 corresponds to 1 cM, allowing the calculation of genetic distances on a chromosome map.