Bias of multicopy arrays to disomic chromosomes/The representation of multicopy arrays on the non-disomic chromosomes was examined using a Monte-Carlo simulation. Using a custom script, each of the genes was placed at random into the genome, weighted for the sizes of the different chromosomes. If the array was placed on a non-disomic chromosome, this was scored, and if the score was the same or higher than the real non-disomic score for that species, the run was counted. Repeating this random analysis a million times for each species gave an empirical P-value for the disomic bias.