Definition of "pleiotropy"

This experimental design is analogous to the experiment that we performed to test whether antagonistic pleiotropy operates as a genetic mechanism in the evolution of late-life mortality rate plateaus.

2011, Laurence D. Mueller, Casandra L. Rauser, Michael R. Rose, Does Aging Stop?, Oxford University Press, page 65

George C. Williams (1957) first developed the idea that pleiotropy might be an important determinant of senescence. Pleiotropy simply means that single genes have multiple effects. With regard to aging, Williams proposed that the same genes could have beneficial effects early in life but detrimental effects late in life. Because the effects are counteracting, the theory has been called "antagonistic pleiotropy."

2015, Lynnette L. Sievert, Chapter 22: Human Senescence, Michael P. Muehlenbein (editor), Basics in Human Evolution, Elsevier (Academic Press), page 315

Much of the recent discussion of the extent of pleiotropy has been stimulated by the work of Gunter Wagner and colleagues (Wagner et al. 2008; Wagner & Zhang 2011), taking advantage of recent methodological advances to test a hypothesis of universal pleiotropy, whereby all traits are affected by each gene.

2016, Mark W. Blows, Katrina McGuigan, 11: The distribution of genetic variance across phenotypic space and the response to selection, Spencer C. H. Barrett, Robert I. Colautti, Katrina M. Dlugosch, Loren H. Rieseberg (editors), Invasion Genetics, Wiley, page 192