Fig. 2
From: Sex gap in aging and longevity: can sex chromosomes play a role?
The contribution of sex chromosomes to sex-specific differences in longevity and possible mechanisms. a The relationship between either female-biased or male-biased adult sex ratios and the sex chromosome type in vertebrates (adapted from [99]). The mechanisms through which sex chromosomes can impact longevity: (b) the unguarded X effect, (c) the toxic Y effect and (d) the loss of Y chromosomes. See text for details