# 3.3. Submodels

The genetic sub-model introduces a source of intra-specific variability of quantitative traits in OSMOSE, through additive genetic variance $$\sigma^2_{A,Z}$$ and expression variance $$\sigma^2_{e,Z}$$ and parental gene inheritance. The individuals are considered diploid hermaphrodites, i.e. without differentiation between males and females, the model being based on female life history. The genotypic values of the four heritable traits—maximum mass-specific ingestion rate $$I_{max}$$, gonado-somatic index $$r$$ , intercept and slope of linear maturation reaction ($$m_0$$ and $$m_1$$, respectively) norm—result from the expression of the corresponding functional loci. Neutral loci have no effect on individuals’ phenotype: their evolution is the result of random drift. Hereafter, the genetic sub-model is described for any of the four evolving traits, generically denoted $$Z$$.