FIGURE 1.

Allele balance (e.g., the distribution of the frequency at which the most abundant allele and the second most abundant allele were sequenced) at heterozygous positions in three Saccharomyces cerevisiae genomes. For each heterozygous genotype the frequency at which the most abundant allele was sequenced at (light blue) and the frequency at which the second most abundant allele was sequenced at (dark blue) were recorded. This information was then summarized with a histogram. Expectations for allele balance are 1/2 for diploids, 1/3 and 2/3 for triploids, and 1/4, 1/2, and 3/4 for tetraploids. This approach provides a dominant copy number for each genome but no information about variation within each genome. Expectations and critical values for binning allele balance information are presented below the histograms.