Fig. 3

A schematic view of genotype-epigenetic-phenotype (G-E-P) map of an individual at a given time. Information from genotype space to phenotype space passes through epigenetic space. Genes (G1 … G8) show cis and trans (gene-gene) interactions. Genes influence phenotypes through biochemical (metabolic) pathways embedded in epigenetic space. Some genes could have major effect on only one phenotype (Mendelian traits, Tr5). On the other hand, many genes with pleiotropic effects influence complex traits (Tr4) and composite traits (Tr1, Tr2, Tr3) which are a constellation of complex traits. Also, some traits (T3, T4) could overlap with other traits, and appear to be independent at the phenotype level may not be independent at all; but could be connected in the epigenetic and genotype space due to pleiotropy. Note that all traits are differentially influenced by a network of genes that show direct, indirect, mediated, conditional, reverse, truncated and merged (H = hub) paths of distribution and dissipation of gene specific enzymes (metabolic flow) as well as post-translational modifications of histones into various components of the phenome (extra-genome). The phenotype is also influenced by age, stage gender, natural and constructed environments (Lewontin 1974; 2000; Wagner 1996; Houle et al. 2010)