The Influence of Phenotypic Modifications on Evolution: The Baldwin Effect and Modern Perspectives

Abstract

A little over one hundred years ago, (1896, 1902) proposed that, is the accommodations which set the pace, lay out the direction, and prophesy the actual course of The idea that individual phenotypic responses to the environment could influence a population's response to selection and facilitate adaptive evolution was also independently proposed by Morgan (1896) and Osborn (1896). The logic of what became known as the Baldwin effect is that phenotypic modifications can potentially allow organisms to survive and reproduce in new environments, in some cases until genetic variation for an appropriate obligate phenotype can be selected (Simpson 1953). For much of this century, however, phenotypic adjustments in response to external (i.e., environmental) or internal forces (i.e., developmental noise) were assumed to slow adaptive divergence by masking genetic variation from natural selection. This presumably reduced the rate at which gene frequencies could change (e.g., Wright 1931, Stebbins 1977, Falconer 1981, Grant 1991). Several recent but disparate studies have again proposed that the capacity to modify the phenotype has a major positive influence on the direction and rate of adaptive divergence (West-Eberhard 1986, 1989, Hinton and Nowlan 1987, Matsuda 1987, Maynard Smith 1987, Wcislo 1989, Nolfi et al. 1994, Papaj 1994, Martins 1996, Turney et al. 1996). While intriguing, none of these studies have sorted out the conflicting views over the association between phenotypic modifications and evolution. Here we (1) give our interpretation of the effect, (2) attempt to relate it to current views of how phenotypic modifications may influence evolution, and (3) suggest further lines of investigation. Historic perspectives