Final answer:
Linkage refers to the inheritance of genes that are close to each other on the same chromosome, often resulting in the co-inheritance of certain traits. This concept challenges classical Mendelian inheritance, as linked genes do not assort independently. The formation of recombination through crossing-over can separate linked genes, depending on their proximity on the chromosome.
Step-by-step explanation:
The phenomenon where genes that are close to each other on a chromosome and tend to be inherited together is known as linkage. The likelihood of genes being inherited together depends on how close they are on the chromosome. During meiosis, linked alleles are more often transmitted together and exhibit linkage patterns different from what the Mendelian laws predict for unlinked or independently assorting genes.
However, during the process of crossing-over in meiosis, there can be an exchange of genetic material between homologous chromosomes. This can separate linked genes, especially if they're not very close to each other on the chromosome, which can lead to recombination. As a result, not all genes on the same chromosome are inherited together, particularly if they are far apart.
Linkage maps are constructed based on the likelihood of crossing-over between genes, which reflects their physical distance from one another on the chromosome. Geneticists leverage these maps to understand the behavior of genes and how traits might be co-inherited.