Costs of phenotypic plasticity can undermine its benefits for evolvable digital organisms

Abstract

Phenotypic plasticity is usually defined as a property of individual genotypes to produce different phenotypes when exposed to different environmental conditions. While the benefits of plasticity for adaptation are well established, the costs associated with plasticity remain somewhat obscure. Understanding both why and how these costs occur could help us explain and predict the behaviour of living creatures as well as allow us to design more adaptable robotic systems. One of the challenges of conducting such investigations concerns the difficulty in isolating the effects of different types of costs and the lack of control over environmental conditions. The present study tackles these challenges by using virtual worlds (software) to investigate the environmentally regulated phenotypic plasticity of digital organisms: the experimental setup guarantees that possibly incurred genetic costs of plasticity are isolated from other plasticity-related costs. The hypothesis put forward here is that despite the potential benefits of plasticity, these benefits might be undermined by the genetic costs related to plasticity itself. This hypothesis was subsequently confirmed to be true. Author summaryPhenotypic plasticity is usually defined as a property of individual DNA that produces different bodies and brains when exposed to different environmental conditions. While the benefits of plasticity for adaptation are well established, there are also potential costs associated with plasticity: "Jack of all trades, master of none." Understanding both why and how these costs occur could help us explain and predict the behaviour of living creatures as well as allow us to design more adaptable robotic systems. While some studies have reported strong evidence for such costs, many other studies have observed no costs. One of the challenges associated with conducting such investigations concerns the difficulty of isolating the effects of the different types of costs. Artificial life (ALife) involves the design and investigation of artificial living systems in different levels of organisation and mediums. Importantly, ALife allows for the customisation of multiple properties of an artificial living system. In the present study, I investigate the environmentally regulated phenotypic plasticity of evolvable digital organisms using an ALife system. The experimental setup guarantees that possibly incurred genetic costs of plasticity are isolated from other plasticity-related costs. The hypothesis put forward here is that despite the potential benefits of plasticity, these benefits might be undermined by the genetic costs related to plasticity itself. This hypothesis was subsequently confirmed to be true.