Beyond these basic, universal features, eukaryotic genomes vary dramatically in terms of size and gene counts. Even so, genome size and the number of genes present in an organism reveal little about that organism's complexity (Figure 1).ne pg is equivalent to approximately 1 billion base pairs.) Therefore, genome size is clearly not an indicator of the genomic or biological complexity of an organism. Otherwise, humans would have at least as much DNA as the marbled lungfish, although probably much more.