Coincidence, coevolution, or causation? DNA content, cell size, and the C-value enigma

Area of Science:

• Evolutionary biology
• Genomics
• Cell biology

Background:

• Genome size variation (C-value enigma) is substantial across eukaryotes but unrelated to organismal complexity.
• Existing theories (mutation pressure, optimal DNA) fail to fully explain genome size diversity and its non-random distribution.
• The nucleotypic theory proposes a direct link between DNA content and cell volume, suggesting selection acts on DNA amount.

Purpose of the Study:

• To review the C-value enigma and proposed explanatory theories.
• To present evidence supporting the nucleotypic theory and its connection to cell size.
• To introduce a novel 'gene nucleus interaction model' for nucleotypic effects.

Main Methods:

• Literature review of theories explaining genome size variation.
• Analysis of evidence supporting the causal link between DNA content and cell volume.
• Development of a new model for nucleotypic influence.

Main Results:

• The C-value enigma remains largely unexplained by mutation pressure or optimal DNA theories.
• The nucleotypic theory, positing selection on DNA content due to cell size impacts, is favored by evidence.
• A new 'gene nucleus interaction model' is proposed to mechanistically explain nucleotypic effects.

Conclusions:

• Genome size variation is under selection, impacting cellular and organismal parameters.
• The nucleotypic theory provides a robust framework for understanding genome size evolution.
• Further empirical investigation is needed to validate the proposed gene-nucleus interaction model and its evolutionary implications.