Fig. 4: Log₂ ratios of ChrY coverage compared to the age of the rats.

a Dot plot showing the median values of the log₂ ratios of ChrY sequencing coverage in young versus old rats. The blue point at value zero represents the log₂ ratio of ChrY from the young rat against itself. The green dot is the sample from old rats with the greatest coverage difference against ChrY from the young rat (Fig. 3h, fifth sample). The arrows point at these values. Significant differences, Linear Model: lm[median.chrY.ratios ~ age]. Exact p values are indicated, * represents P < 0.05. b Dot plot of the median values of the log₂ ratios against its variance. Significant differences, Linear Model: lm[variance.ratios ~ median.chrY.ratios]. Exact p values are indicated, * represents P < 0.05; *** represents P < 0.001. The results from two linear models are shown: the linear tendency in light grey includes all data points, whereas the linear tendency in black excluded the blue dot (young ChrY) and the green dot (ChrY with the lowest log₂ ratio). The arrows point at these values.