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ABSTRACT Males of polygynous mammals often do not live as long as females and, in some cases, exhibit evidence of earlier senescence. Patterns of DNA methylation (DNAm) have recently been used to predict chronological age in mammals. Whether DNAm also changes as a consequence of survival and senescence is largely untested in wild animals. In this study, we estimate mortality rates using recaptures of 2700 greater spear‐nosed bats,Phyllostomus hastatus, over 34 years and DNAm profiled for over 300 adult bats. In this species, one male typically controls mating access to a group of unrelated females. Bayesian analysis reveals that mortality risk in males is 1.8 times that of females, and comparison of age‐associated differences in DNAm indicates that DNAm changes 1.4 times faster in males than females. Therefore, even though the age of either sex is predicted by a common set of sites, the methylome of males is more dynamic than that of females. Sites associated with sex differences in the rate of DNAm change are sensitive to androgens and enriched on the X chromosome. Sites that exhibit hypermethylation are enriched in promoters of genes involved in the regulation of metabolic processes. Unexpectedly, subordinate males have higher mortality rates than reproductively dominant males and exhibit faster DNAm change than dominants at dozens of sites. Our results reveal that differences in mortality associated with sex and social status are reflected by changes in DNA methylation, providing novel insights into mechanisms of aging and mortality in this and likely other wild animal populations. 

ABSTRACT Telomeres, protective caps at the ends of linear chromosomes, are frequently found to shorten with age. Telomere length is commonly measured in wild populations to investigate age‐related changes in somatic integrity and is considered a hallmark of ageing. Despite interest, there is no clear picture regarding sex differences in telomere length or rate of attrition across species. Bats are of considerable interest in studies of ageing and telomeres, owing to their remarkable longevity and the absence of age‐associated telomere attrition observed in some species. Additionally, multiple bat species show evidence of sex differences in longevity. However, few studies of bat telomeres have included both sexes. We collected DNA from wild‐caught males and females of the highly polygynous greater spear‐nosed bat,Phyllostomus hastatus, in which mortality is strongly male‐biased, and measured relative telomere lengths. We found that, while telomeres were shorter in older bats, there was no evidence of shorter telomeres in males. In fact, males tended to have longer telomeres. This runs counter to our prediction of shorter telomeres in the shorter‐lived sex but is not completely unexpected in light of other observations, including that of shorter telomeres in longer lived species.