PLoS Genet. 6, e1001080 (2010)

Why does genome size vary so widely among species — even among those of the same family? Population size is one proposed answer: mutations that increase genome size are harmful, and selection would more efficiently weed out such mutations in species with a higher head count.

According to Kenneth Whitney of Rice University in Houston, Texas, and Theodore Garland at the University of California, Riverside, the original analysis of 30 species that underlies this idea may flawed. When the duo reanalysed the data — this time accounting for the evolutionary relationships between species, because shared history may mean similar population and genome sizes — they found no clear link between population size and genome size.