Base Composition Patterns

Abstract

Abstract Genomic GC content varies both between species and within individual genomes. The nature of this variation differs between groups of organisms. Bacteria exhibit little intragenomic variation in GC content, but a large range of variation between species. In contrast, higher eukaryotes exhibit a much narrower range of variation in GC content between species, but many have highly structured variation within their genomes, which may reflect a fundamental level of genome organisation. The causes of variation in GC content have been subject to debate, and it has been suggested that both natural selection and mutational biases may play a role. However, at least in vertebrates, much recent evidence points to a strong role of recombination in determining base composition patterns. Key Concepts: GC content shows considerable variation between species and within genomes. GC content is rarely at equilibrium, and changes over evolutionary time. Recent evidence points to a strong role of recombination in determining GC content.