Which concept asserts that alleles can mask the effect of other alleles?

Dominance is the concept that describes how certain alleles can mask the effects of others when both are present in a heterozygous genotype. In a situation where an individual has two different alleles for a particular gene, the dominant allele will overshadow the influence of the recessive allele. For instance, in a typical Mendelian trait, if "A" represents a dominant allele and "a" a recessive allele, an organism with the genotype "Aa" will express the trait associated with "A," effectively hiding the trait linked to "a."

This concept helps explain why certain traits appear in individuals while others do not, depending on the alleles they inherit from their parents. In contrast, the other concepts like segregation deal with the separation of alleles during gamete formation, independent assortment pertains to how different genes independently separate from one another when reproductive cells develop, and gene linkage refers to the tendency of alleles located close together on a chromosome to be inherited together. These concepts do not specifically indicate how one allele can overshadow the influence of another, which is the essence of dominance.