Fig. 2

Gene family expansion and contraction. A Gene family expansion and contraction across a phylogenetic tree of 30 mammals. The numbers of expanded and contracted gene families in each species are shown in red and green, respectively. Scrotal CDT species are indicated by blue shading; ascrotal IDT and UDT species are indicated by yellow and red shading, respectively. Silhouettes of mammalian species are reproduced from http://phylopic.org/ under a Public Domain or Creative Commons license. B Phylogenetic ANOVA of the numbers of expanded and contracted gene families in ascrotal and scrotal mammals. C Phylogenetic ANOVA of the numbers of expanded and contracted gene families in CDT, IDT, and UDT mammals. Only the number of gene family expansions in IDT and UDT were significantly different (p-value = 0.036)