Adult telomere length is positively correlated with survival and
lifetime reproductive success in a wild passerine
Abstract
Explaining variation in individual fitness is a key goal in evolutionary
biology. Recently, telomeres, repeating DNA sequences capping the ends
of chromosomes, have gained attention as a biomarker for body state,
individual quality, and ageing. However, existing research has provided
mixed evidence for whether telomere length correlates with fitness
components, including survival and reproductive output. Moreover, few
studies have examined how telomere shortening correlates with fitness in
wild populations. Here, we intensively monitored an insular population
of house sparrows on Lundy Island, UK, and collected longitudinal
telomere and life history data spanning 16 years from 1,225 individuals.
We tested whether telomere length and/or shortening predict fitness
measures, namely survival, lifespan, as well as annual and lifetime
reproductive success. Telomere length positively predicted immediate
survival up to one year after measurement, independent of age, but did
not predict lifespan, suggesting either a diminishing telomere length –
survival correlation with age, or other extrinsic factors of mortality.
The positive effect of telomere length on survival translated to
reproductive benefits, as birds with longer telomeres produced more
genetic recruits over their lifetime, but not annually, suggesting
variation in individual quality. The rate of telomere shortening,
however, correlated with neither lifespan nor lifetime reproductive
success. Our results provided further evidence that telomere length
correlates with fitness, and they contributed to our understanding of
how telomere dynamics link with individual quality.