A New Perspective on Type-Token Distinction in the Genotype and Phenotype Concepts

Abstract

The genotype-phenotype distinction is a core theoretical framework in biology. Genotype and phenotype classify biological entities or organisms as groups of individuals (the tokens) that share a common identity (the type), but so far it has not been investigated how these two concepts classify their tokens as types. However, this is key to defining which biological entities can and cannot be denoted by genotype and phenotype, a prerequisite to properly understand the so-called nongenetic inheritance. Here, we analyze type-token relations in genotype and phenotype and propose a new framework to differentiate these concepts by how they classify their tokens. We first argue that genotypes should be defined independently of genes, distinguishing genotype (classification of whole inherited structures) from genetype (classification of genes). Second, we propose that genotypes are natural kinds because they replicate and conserve their type-identity by self-templating, independently from being intentionally classified by humans. Conversely, phenotypes would not constitute natural kinds, as their tokens are intentionally classified. Finally, the identification of self-templating as a fundamental genotypic property opens new avenues to include additional inherited structures that are different to the genome, as parts of the full genetic identity of organisms, of their genotype.