Life History and the Male Mutation Bias

Abstract

If DNA replication is a major cause of mutation, then those life-history characters, which are expected to affect the number of male germline cell divisions, should also affect the male to female mutation bias (alpha(m)). We tested this hypothesis by comparing several clades of bird species, which show variation both in suitable life-history characters (generation time as measured by age at first breeding and sexual selection as measured by frequency of extrapair paternity) and in alpha(m), which was estimated by comparing Z-linked and W-linked substitution rates in gametologous introns. Alpha(m) differences between clades were found to positively covary with both generation time and sexual selection, as expected if DNA replication causes mutation. The effects of extrapair paternity frequency on alpha(m) suggests that increased levels of sexual selection cause higher mutation rates, which offers an interesting solution to the paradox of the loss of genetic variance associated with strong directional sexual selection. We also used relative rate tests to examine whether the observed differences in alpha(m) between clades were due to differences in W-linked or Z-linked substitution rates. In one case, a significant difference in alpha(m) between two clades was shown to be due to W-linked rates and not Z-linked rates, a result that suggests that mutation rates are not determined by replication alone.

Evolutionary and Biomedical Insights from the Rhesus Macaque Genome

“…This value is lower than a = 6 estimated for the human and chimpanzee (58) but higher than a = 2 estimated for the mouse and rat (3,59). Thus, this argues against a uniform magnitude of male mutation bias in mammals (5) and supports a correlation between male mutation bias and generation time (60,61).…”

Fast-X on the Z: Rapid evolution of sex-linked genes in birds

“…Moreover, when mutations are partly dominant, male-biased mutation implies that Z-linked genes evolve faster than autosomal loci over a broader range of dominance values than is the case for X-linked genes (Kirkpatrick and Hall 2004a). Admittedly, the excess of paternally derived mutation in birds is relatively weak, with recent estimates of the male-tofemale mutation rate ratio (␣ m ) of ∼2.5 (Bartosch-Härlid et al 2003;Axelsson et al 2004), suggesting that the role of malebiased mutation is weak in our analysis. However, male-biased mutation is much more pronounced in some mammals, in particular, primates (Makova and Li 2002).…”

The Chicken (Gallus gallus) Z Chromosome Contains at Least Three Nonlinear Evolutionary Strata

“…The W chromosome is only transmitted through the female germline and has therefore the female mutation rate. Previous work in birds has indicated that the male mutation rate is two to four times higher than the female rate (Bartosch-Härlid et al 2003;Axelsson et al 2004;Berlin et al 2006). In galliforms, the Z chromosome rate is slightly higher than the autosomal rate, whereas the W chromosome rate is about half the autosomal rate (Axelsson et al 2004).…”