Genome Sizes Vary Tremendously Among Organisms

Genome sizes vary tremendously among organisms.Size does not directly correlate with complexity, as organisms that have similar complexities can differ by as much as 40 times.Yet, these same organisms may have similar numbers of genes, with noncoding DNA making up the tremendous difference in genome sizes.One hypothesis is that the proportion of coding to noncoding DNA in the genome of a species is related to the sizes of the populations typical of the species.Explain how the coding-to-noncoding DNA ratios in species with different typical population sizes might be related to the relative importance of natural selection and genetic drift in the evolution of the species.