What is it called when a single gene influences multiple traits?

When a single gene influences multiple traits, this phenomenon is known as pleiotropy. Pleiotropy occurs when one gene affects multiple seemingly unrelated phenotypic traits. This can happen because the gene may produce a protein that is involved in different biochemical pathways or has various effects in different tissues of the organism.

For example, consider the gene responsible for the coloration of fur in some animals. This same gene may also affect the animal's metabolism or size. As a result, a mutation in this gene could lead to changes in both color and other traits, illustrating how one gene can have multiple impacts on an organism's overall characteristics.

In contrast, polygenic inheritance refers to the influence of multiple genes on a single trait, while multiple alleles describe the occurrence of more than two alleles for a gene in a population. Complete dominance refers to the relationship between alleles where one dominant allele completely masks the effect of a recessive allele. These concepts highlight the complexity of genetic inheritance and the diverse ways genes can influence traits.