Abstracts (first author)
The impact of age-related changes in fertility: implications for sexual conflict
Summary:
The impact of age on evolutionary processes is a relatively under-appreciated consideration in biology, despite differential effects on reproductive physiology between females and males. It is not expected that fertility will decline evenly between the sexes, since different traits determine fertility in each sex. Using a large, pedigreed laboratory population, we conducted a quantitative genetic study of fertility in a common European rodent, the bank vole (Myodes glareolus), to explore how senescent changes affect coevolution between the sexes. Our results indicate that reproductive success, as measured by litter size in females and offspring sired in males, differentially declined according to sex, with females experiencing a sharper decline in their fertility than males. The genetic correlation between the sexes for fertility was not significant for younger individuals, but became significantly negative for older individuals that reproduced. The age-dependent expression of fitness-related genes results in a divergence of reproductive interests between the sexes. Furthermore, the additive genetic variance for female fertility increased with age, consistent with the process of relaxed selection in older age. These results will be discussed in the broader context of sexual conflict theory.
