Noncoding DNA as a Phenotypic Driver

The genotype-phenotype interactions has been a core topic in biology since the seminal works of Weismann that distinguished between the genotype transmitted by the germ cells to the phenotype of the developing individual that was shaped by a combination of traits coded for by the genotype and environmental impacts. While the genotype-phenotype discussion primarily concerns genotype in the sense of alleles or copy-number of protein-coding genes including regulatory elements, the impact of non-protein coding elements like transposons on the phenotype has been recognized for several decades. Transposons constitute a major share of most genomes, and genome size per se display a tremendous variability even between closely related organisms. The extent to which this affect morphology and a range of fitness-related phenotypic traits like cell size, body size, morphology, growth rate, behavior, life cycle and potentially also speciation calls for a closer attention towards genome size as phenotypic determinant.