Evolutionary significance of plastic responses within and across generations

Until recently, all the resemblances between parents and their offspring were often ascribed to genes. Indeed, there is no doubt that DNA plays a central role in heredity. However, in recent years, it has become apparent that various non-genetic factors, independent of the DNA sequence, can also be passed from one generation to another, and in some cases even over as many as 80 generations. These effects include phenomena such as parental effects and epigenetic inheritance; two forms of trans-generational plasticity. In contrast to trans-generational plasticity, which allows for trait transmission across multiple generations, within-generational plasticity acts within one generation and includes phenomena such as environment-specific trait expression or catch-up growth. Plastic responses are especially advantageous in heterogeneous environment in which genetic mutations may not arise fast enough to allow organisms to cope with new conditions. In such cases, plastic responses may offer a better strategy and character of the environment will determine which form of plastic responses will be present. Both within-and trans-generational plasticity may alter the rate and direction of adaptation and can therefore have important implications for evolution. However, each type of plastic response is distinct and will thus alter adaptation in a unique way. Here I provide a detailed description of some of the most important forms of plastic responses and their consequences for adaptation