Final answer:
The site in the genome used to track alleles and closely linked loci is called a marker locus, which is crucial for genetic mapping and studying genetic recombination and linkage.
Step-by-step explanation:
A site in the genome where a simple test will reveal which alleles are present and is often used to track nearby, closely linked loci is known as a marker locus. Marker loci are used in genetic mapping as landmarks, in a similar way to how a road map uses physical landmarks. They allow scientists to track the inheritance of genes and are key in understanding the genetic recombination and linkage of specific traits. These markers are often polymorphic, meaning they show variability within a population, making them useful for comparing the genomes of individuals within that population to identify genetic differences and associations with particular traits.