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bioRxiv · 10.1101/2025.11.26.690843

Widespread sex-biased gene expression reflects female-biased longevity in a species with environmental sex determination

Bock, S.·Hoekstra, L. A.·Hagerty, K.·Schmidt, R. E.·Judson, J.·Adorsoo, M.·Singh, R.·Janzen, F. J.·Bronikowski, A. M.
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Abstract

Sexes frequently differ in life history traits including body size, lifespan, and age at sexual maturity. Aging, the progressive decline in physiological function and cellular resilience over time, is a central process contributing to sex-specific life histories, yet the mechanisms driving sex differences in aging remain largely unresolved. Long-term mark-recapture efforts revealed a striking pattern of female-biased longevity in the painted turtle (Chrysemys picta), a species with temperature-dependent sex determination. As a result, this species provides a compelling system to examine the mechanisms of sex-specific aging in the absence of sex chromosomes. Here, we characterize sex- and age-associated patterns in the blood transcriptomes of wild painted turtles (n = 93). We identified widespread gene expression differences between females and males (2,347 genes; 13.4% of all filtered genes). In contrast, only six genes showed significant linear relationships with continuous age in both sexes. We also employed a machine learning approach which identified distinct sets of genes for which expression was predictive of age in each sex. Age-related gene expression patterns highlight both conserved molecular pathways with known roles in aging as well as novel gene targets. These findings suggest sex-specific molecular processes underlie sex-biased demographic aging and raise questions regarding the environmental and developmental drivers of sex-biased gene expression.

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Bock, S., Hoekstra, L. A., Hagerty, K., Schmidt, R. E., Judson, J., Adorsoo, M., Singh, R., Janzen, F. J., Bronikowski, A. M.. 2025-12-01. Widespread sex-biased gene expression reflects female-biased longevity in a species with environmental sex determination. https://doi.org/10.1101/2025.11.26.690843

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