Overview of levels of lineage-specific positive selection on telomere associated genes in each lineage of mammal. Each of the 52 telomere associated genes are categorized into 4 major functional groups (colour coded as per pie chart inset). On the left is the placental mammal phylogeny used. The maximum length of each horizontal bar in the histogram depicts the overall number of times that species was represented in the total dataset of 52 gene families. The shaded portions of the bars correspond to the functional categories (as per colour scheme in the pie chart), the size of these shaded regions represents the proportion of genes in that category that are identified as having undergone lineage-specific positive selection.