Mechanism of evolution by genetic assimilation
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Conrad H. Waddington discovered the phenomenon of genetic assimilation through a series of experiments on fruit flies. In those experiments, artificially exerted environmental stress induced plastic phenotypic changes in the fruit flies, but after some generations, the same phenotypic variant started to appear without the environmental stress. Both the initial state (where the phenotypic changes were environmentally induced and plastic) and the final state (where the phenotypic changes were genetically fixed and constitutive) are experimental facts. However, it remains unclear how the environmentally induced phenotypic change in the first generation becomes genetically fixed in the central process of genetic assimilation itself. We have argued that the key to understanding the mechanism of genetic assimilation lies in epigenetics, and proposed the “cooperative model” in which the evolutionary process depends on both genetic and epigenetic factors. Evolutionary simulations based on the cooperative model reproduced the process of genetic assimilation. Detailed analysis of the trajectories has revealed genetic assimilation is a process in which epigenetically induced phenotypic changes are incrementally and statistically replaced with multiple minor genetic mutations through natural selection. In this scenario, epigenetic and genetic changes may be considered as mutually independent but equivalent in terms of their effects on phenotypic changes. This finding rejects the common (and confused) hypothesis that epigenetically induced phenotypic changes depend on genetic mutations. Furthermore, we argue that transgenerational epigenetic inheritance is not required for evolution by genetic assimilation.
KeywordsEpigenome Phenotype-driven evolution Phenotypic plasticity Evo-Devo Evolutionary synthesis Simulation
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Conflict of interests
Ken Nishikawa declares that he has no conflict of interest. Akira R. Kinjo declares that he has no conflict of interest.
This article does not contain any studies with human participants or animals performed by any of the authors.
- Barton NH, Briggs DEG, Eisen JA, Goldstein DB, Patel NH (2007) Evolution. Cold Spring Harbor Laboratory Press, New YorkGoogle Scholar
- Crow JF, Kimura M (1970) An introduction to population genetics theory. Harper and Row Publishers, New York. reprinted in 2009 by Blackburn PressGoogle Scholar
- Fraga MF, Ballestar E, Paz MF, Ropero S, Setien F, Ballestar ML, Heine-Suñer D, Cigudosa JC, Urioste M, Benitez J, Boix-Chornet M, Sanchez-Aguilera A, Ling C, Carlsson E, Poulsen P, Vaag A, Stephan Z, Spector TD, Wu YZ, Plass C, Esteller M (2005) Epigenetic differences arise during the lifetime of monozygotic twins. Proc Natl Acad Sci USA 102:10:604–10:609. https://doi.org/10.1073/pnas.0500398102 CrossRefGoogle Scholar
- Gilbert S, Epel D (2009) Ecological developmental biology: integrating epigenetics, medicine, and evloution. Sinauer Associates Inc., SunderlandGoogle Scholar
- Goldschmidt RB (1938) Physiological Genetics. McGraw-Hill, New YorkGoogle Scholar
- Matsuda R (1987) Animal evolution in changing environments: with special reference to abnormal metamorphosis. Wiley, LondonGoogle Scholar
- Ohta K (2013) Epigenome and Life. Kodansha, TokyoGoogle Scholar
- Pigliucci M, Müller GB (eds) (2010) Evolution, the extended synthesis. MIT Press, CambridgeGoogle Scholar
- Waddington CH (1957) The strategy of the genes. Allen and Unwin, LondonGoogle Scholar
- West-Eberhard MJ (2003) Developmental plasticity and evolution. Oxford University Press, OxfordGoogle Scholar