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Demographic factors are fundamental in shaping infectious disease dynamics. Aspects of populations that create structure, like age and sex, can affect patterns of transmission, infection intensity and population outcomes. However, studies rarely link these processes from individual to population-scale effects. Moreover, the mechanisms underlying demographic differences in disease are frequently unclear. Here, we explore sex-biased infections for a multi-host fungal disease of bats, white-nose syndrome, and link disease-associated mortality between sexes, the distortion of sex ratios and the potential mechanisms underlying sex differences in infection. We collected data on host traits, infection intensity and survival of five bat species at 42 sites across seven years. We found females were more infected than males for all five species. Females also had lower apparent survival over winter and accounted for a smaller proportion of populations over time. Notably, female-biased infections were evident by early hibernation and likely driven by sex-based differences in autumn mating behaviour. Male bats were more active during autumn which likely reduced replication of the cool-growing fungus. Higher disease impacts in female bats may have cascading effects on bat populations beyond the hibernation season by limiting recruitment and increasing the risk of Allee effects.
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This content will become publicly available on May 15, 2026
Sex differences in DNA methylation in bats
Sex-biased longevity is observed across a wide range of animal taxa, including bats, for reasons not well understood. Patterns of cytosine methylation vary predictably with age in many organisms, offering a valuable means to investigate differences in patterns of aging at the molecular level. We tested sex differences in cytosine methylation across 14 bat species and compared patterns of age-associated variation. Sex differences were overrepresented on the X chromosome, showing a strong pattern of female hypermethylation within promoter regions. Sex and age-associated differences in methylation were non-randomly distributed with respect to proximity to putative sex hormone receptor binding sites, with sites hypermethylated in males and females tending to be underrepresented near androgen and estrogen receptor binding sites, respectively. Across species, we observed the relative steepness of male versus female slopes of age-associated variation was associated with the strength of precopulatory sexual selection, with especially strong trends towards male-biased age-associated slopes in two harem-polygynous species that exhibit female-biased longevity. Our results offer insights into how patterns of methylation differ across sexes and ages, and raise intriguing questions for future research, such as whether sex differences in molecular aging reflect sex-biased longevity, for which records in bats are sparse.
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- Award ID(s):
- 2213824
- PAR ID:
- 10592626
- Publisher / Repository:
- bioRxiv
- Date Published:
- Format(s):
- Medium: X
- Institution:
- bioRxiv
- Sponsoring Org:
- National Science Foundation
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