Telomeres positively correlate with pace-of-life and elongate with age
in a wild mammal
Abstract
Understanding ageing and the diversity of life histories is a
cornerstone in biology. Telomeres, the protecting caps of chromosomes,
are thought to be involved in ageing, cancer risks and to modulate
life-history strategies. They shorten with cell division and age in
somatic tissues of most species, possibly limiting lifespan. The
resource allocation trade-off hypothesis predicts that short telomeres
have thus co-evolved with early reproduction, proactive behaviour and
reduced lifespan, i.e. a fast Pace-of-Life Syndrome (POLS). Conversely,
since short telomeres may also reduce the risks of cancer, the
anti-cancer hypothesis advances that they should be associated with slow
POLS. Conclusion on which hypothesis best supports the role of telomeres
as mediators of life-history strategies is hampered by a lack of study
on wild short-lived vertebrates, apart from birds. Using seven years of
data on wild Eastern chipmunks Tamias striatus, we highlighted that
telomeres elongate with age and do not limit lifespan in this species.
Furthermore, short telomeres correlated with a slow POLS in a
sex-specific way. Females with short telomeres had a delayed age at
first breeding and a lower fecundity rate than females with long
telomeres, whereas those differences were not recorded in males. Our
findings support most predictions adapted from the anti-cancer
hypothesis, but none of those made under the resource allocation
trade-off hypothesis. Results are in line with an increasing body of
evidence suggesting that resource allocation trade-offs alone cannot
explaining the diversity of telomere length in adult somatic cells and
life-histories observed across the tree of life.