What is pleiotropy?

Pleiotropy refers to the phenomenon where a single allele or gene influences multiple phenotypic traits. This means that changes or variations in one gene can lead to effects on different characteristics in an organism. For instance, a single gene may be responsible for determining not just one physical characteristic, like coloration, but also influence other aspects such as growth rate or behavior. This is important in understanding the complexity of genetics, as it illustrates how the interplay between genes can lead to diverse and multi-faceted traits arising from single genetic changes.

The other options address ideas related to genetics but do not accurately define pleiotropy. The expression of multiple phenotypes from one gene is too broad and does not specifically highlight the role of a single allele affecting multiple traits, which is central to pleiotropy. The impact of environmental factors on genes refers to gene expression influenced by environmental conditions, which is different from the concept of one gene affecting multiple traits. A type of genetic mutation affecting one trait would be a more localized effect and does not encompass the broader implications of pleiotropy, which inherently involves multiple traits being influenced by a single gene or allele.