phenotypic plasticity
Ghalambor CK, McKay JK, Carroll SP & Reznick DN 2007 Adaptive versus non-adaptive phenotypic plasticity and the potential for contemporary adaptation in new environments. Funct Ecol 21:394-407.
- by definition any plasticity that allows individuals to have higher fitness in the new environment than it would were it not plastic will be beneficial
- this does not mean that the reaction norm for a given trait was necessarily shaped by natural selection (i.e. be an adaptation in itself)
- it is necessary to specify the impact different kinds of plasticity might have in the face of directional selection
- a second step of adaptation to new environments via adaptive plasticity can be the conversion of non-heritable environmentally induced variation to heritable variation
- a scenario that remains controversial despite theoretical and empirical arguments dating back over a century
- the process by which non-heritable environmentally induced variation leads to adaptive heritable variation is often referred to as the Baldwin Effect or more commonly as genetic assimilation
- genetic assimilation is when traits that were originally environmentally induced become (by the process of directional selection) genetically determined and canalized (a loss of plasticity or a flat reaction norm)
- a less restrictive term genetic accommodation, which does not necessarily lead to a loss in plasticity
