Final answer:
The measure used to determine shared autosomal regions between individuals is centimorgans (cM), which reflect genetic distances based on crossover frequency. This is important in mapping genes on chromosomes and tracing ancestry.
Step-by-step explanation:
The extent of shared autosomal regions between individuals, which provides ancestry information, is measured in centimorgans (cM). Autosomal inheritance involves the genes on the 22 non-sex chromosomes, and their patterns reveal how traits are passed down through generations. When geneticists construct gene maps on chromosomes, they do so by analyzing crossover frequency—specifically, instances where offspring exhibit nonparental genotypes.
Understanding these genetic linkages and the concept of autosomal inheritance can help determine phylogenies and trace an individual’s ancestry. The shared DNA across different organisms, analyzed through sophisticated computer algorithms, provides insights into evolutionary histories and how closely two individuals are related in terms of shared ancestry.