Abstract
AbstractTelomeres are repeating DNA sequences found on the ends of chromosomes, which shorten with age and are implicated in senescence. Cross-species analyses of telomere shortening rates (TSR) and telomere lengths are important for understanding mechanisms underlying senescence, lifespan and life-history strategies of different species. Whittemore et al. (2019) generated a new dataset on variation in TSR, lifespan and body mass. In phylogenetically uncorrected analyses they found that TSR negatively correlates with lifespan. We re-ran analyses of their dataset using appropriate phylogenetic corrections. We found a strong phylogenetic signal in the association between TSR and body mass. We were able to corroborate Whittemore et al.’s major findings, including while correcting for body mass in a multivariate analysis. Since laboratory mice have different telomere lengths and potentially different telomere dynamics than wild mice, we removed mice from the analysis, which attenuates most associations.
Highlights
Telomeres are repeating DNA sequences found on the ends of chromosomes which shorten with age and are implicated in senescence
Re-analyzing the primary findings from WEA with appropriate phylogenetic regressions leaves the general findings of WEA intact (Table 1)
Re-analyzing the WEA dataset with phylogenetic corrections and excluding the laboratory mouse (C57BL/6 strain) weakens all results (Table 1)
Summary
Telomeres are repeating DNA sequences found on the ends of chromosomes which shorten with age and are implicated in senescence. Whittemore et al (2019), hereafter WEA, recently generated a dataset of cross-sectional telomere shortening rates across nine different tetrapod species using the quantitative fluorescence in situ hybridization technique to measure telomere length. They found a strong negative relationship between telomere shortening rates and lifespan. Not controlling for the phylogenetic relationship between species implicitly assumes a “star phylogeny” in which all species are related to each other or that the traits in question are not influenced by phylogeny (Felsenstein, 1985). We exclude the laboratory mouse in some of our analyses out of concern that laboratory mice have been shown to have considerably longer telomeres than their wild counterparts possibly due to artificial selection and/or inbreeding (Eisenberg, 2011; Kotrschal et al, 2007; Manning et al, 2002; Weinstein & Ciszek, 2002)
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