Final Answer:
Linkage between genes affects the inheritance of characters by influencing their co-segregation during meiosis. Morgan's experiments on fruit flies demonstrated linked genes on the same chromosome and introduced the concept of crossing over, where genetic material is exchanged between homologous chromosomes during meiotic recombination.
Step-by-step explanation:
Inheritance of characters is often influenced by the location of genes on chromosomes. If genes are located on the same chromosome and are close to each other, they tend to be inherited together due to a phenomenon known as linkage. Thomas Morgan's experiments with fruit flies, particularly Drosophila melanogaster, provided crucial insights into the concept of linked genes.
Morgan observed that certain traits, which were presumed to assort independently according to Mendelian principles, showed patterns of inheritance that deviated from the expected ratios. This led him to propose that these genes were physically linked on the same chromosome. The degree of linkage is influenced by the physical distance between genes; closer genes are more likely to be inherited together.
Furthermore, Morgan's work contributed to the understanding of crossing over, a process that occurs during meiosis. Crossing over involves the exchange of genetic material between homologous chromosomes, leading to the recombination of linked genes. This phenomenon contributes to genetic diversity by generating new combinations of alleles.
The mechanism of crossing over was later explained by the breakage and reunion of chromatids at specific points, known as chiasmata. The frequency of crossing over between linked genes is proportional to the physical distance between them. Morgan's experiments laid the foundation for understanding the complexities of genetic linkage and recombination, providing key insights into the mechanisms of inheritance.