Fig. 5.

Genes retained on the Y chromosome in strata one and two are more likely to exhibit haploinsufficiency. Human proteins with predicted haploinsufficiency indexes were matched to one-to-one human-threespine stickleback fish orthologs from the X chromosome. Haploinsufficiency indexes were significantly lower for genes retained on both the X and Y chromosomes than for genes present only on the X chromosome (i.e., lost from the Y chromosome) in both strata one and two. A lower index indicates that a gene is more likely to be haploinsufficient. The total number of genes in each category is shown. The median is indicated by the solid black line. Whiskers denote 1.5x the interquartile range. Outliers are not shown. Asterisks indicate P < 0.05 (Mann-Whitney U test)