What is Antagonistic Pleiotropy?

Abstract

Antagonistic Pleiotropy has been the dominant theory for evolution of aging since it was first proposed 60 years ago. Indeed, examples of pleiotropy have been observed, but there are also many examples of mutations that lead to longer lifespan without apparent cost. This poses a dilemma for the logic of the theory, which depends critically on the assumption that pleiotropy has imposed an inescapable precondition on evolution. Another interpretation is possible for the pleiotropy observed in nature. Natural selection may actually favor pleiotropy as an evolved adaptation. This is because the combination of high fertility and long lifespan is a temptation for individuals, but a danger for the health of populations. Predator populations that grow faster than their prey can recover are at risk of extinction. Once a sustainable mix of fertility and longevity has been established by multilevel natural selection, pleiotropy can help to assure that it is not lost. The population is free to shift from (high fertility/short lifespan) to (lower fertility/longer lifespan) as varying environmental conditions demand, without risking population overshoot and collapse. I describe herein experiments with an individual-based computer simulation in which pleiotropy evolves as a group-selected adaptation under a range of assumptions and in a broad swath of parameter space.