Determination of sample ploidies/To determine individual chromosome ploidies per isolate the GATK tool ‘DepthOfCoverage’ (RRID:SCR_001876, v2.6–4) was used to obtain per-base read depth applying parameters: ‘--omitIntervalStatisticsX--omitLocusTableX--includeRefNSitesX--includeDeletionsX--printBaseCounts’. Results files were masked using our custom mask (see ‘Reference Genome Mask’). Summary statistics were calculated per chromosome, including median read depth. The median read depth for each chromosome was used to estimate chromosome copy number, somy, for each sample using an Expectation-Maximization approach previously described in Iantorno et al. (2017). For a few isolates where the coverage model appeared to be overfitting (high deviance values), somy estimates were manually curated by examining both coverage and allele frequency data. Where allele frequency distributions did not support high somy values, they were altered so that the majority of chromosomes were disomic and individual errors were corrected to fit clear somy expectations suggested by the respective allele frequency spectra.