HYPOTHESIS AND THEORY ARTICLE
Front. Genet., 19 May 2015 | https://doi.org/10.3389/fgene.2015.00179
The differential view of genotype–phenotype relationships
Virginie Orgogozo1*, Baptiste Morizot2 and Arnaud Martin3
1 CNRS, UMR 7592, Institut Jacques Monod, Université Paris Diderot, Paris, France
2 Aix Marseille Université, CNRS, CEPERC UMR 7304, Aix en Provence, France
3 Department of Molecular Cell Biology, University of California, Berkeley, CA, USA
FIGURE 2. Three current graphical representations of GP maps. (A) The early version of the GP map proposed by Lewontin (1974a). (B) A GP map where each point represents a single individual (Houle et al., 2010; Gjuvsland et al., 2013; Salazar-Ciudad and Marín-Riera, 2013). (C) The relationships between traits and genes, as depicted by Wagner (1996). See text for details.
We sometimes seem to have forgotten that the original question in genetics was not what makes a protein but rather ‘what makes a dog a dog, a man a man.’
Denis Noble, 2006
Abstract
An integrative view of diversity and singularity in the living world requires a better understanding of the intricate link between genotypes and phenotypes. Here we re-emphasize the old standpoint that the genotype–phenotype (GP) relationship is best viewed as a connection between two differences, one at the genetic level and one at the phenotypic level. As of today, predominant thinking in biology research is that multiple genes interact with multiple environmental variables (such as abiotic factors, culture, or symbionts) to produce the phenotype. Often, the problem of linking genotypes and phenotypes is framed in terms of genotype and phenotype maps, and such graphical representations implicitly bring us away from the differential view of GP relationships. Here we show that the differential view of GP relationships is a useful explanatory framework in the context of pervasive pleiotropy, epistasis, and environmental effects. In such cases, it is relevant to view GP relationships as differences embedded into differences. Thinking in terms of differences clarifies the comparison between environmental and genetic effects on phenotypes and helps to further understand the connection between genotypes and phenotypes.
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