Abstract
Telomere length (TL) has become a biomarker of increasing interest within ecology and evolutionary biology, and has been found to predict subsequent survival in some recent avian studies but not others. Here, we undertake the first formal meta-analysis to test whether there is an overall association between TL and subsequent mortality risk in vertebrates other than humans and model laboratory rodents. We identified 27 suitable studies and obtained standardized estimates of the hazard ratio associated with TL from each. We performed a meta-analysis on these estimates and found an overall significant negative association implying that short telomeres are associated with increased mortality risk, which was robust to evident publication bias. While we found that heterogeneity in the hazard ratios was not explained by sex, follow-up period, maximum lifespan or the age group of the study animals, the TL–mortality risk association was stronger in studies using qPCR compared to terminal restriction fragment methodologies. Our results provide support for a consistent association between short telomeres and increased mortality risk in birds, but also highlight the need for more research into non-avian vertebrates and the reasons why different telomere measurement methods may yield different results.This article is part of the theme issue ‘Understanding diversity in telomere dynamics’.
Highlights
Telomeres are highly repetitive sections of DNA that cap the ends of chromosomes in most eukaryote species, forming complexes with so-called ‘shelterin’ proteins that are essential to the maintenance of genomic integrity of linear chromosomes [1,2]
We found that short telomere length (TL) was associated with increased risk of mortality, and that this result is robust to correction for evident publication bias
While many recent papers have cited a handful of salient examples as evidence for such a general pattern, here we provide the first formal test to support a TL–mortality association across studies of non-human vertebrates
Summary
Telomeres are highly repetitive sections of DNA that cap the ends of chromosomes in most eukaryote species, forming complexes with so-called ‘shelterin’ proteins that are essential to the maintenance of genomic integrity of linear chromosomes [1,2]. The majority of non-human research into telomere biology has been performed in laboratory rodents, studies beyond model organisms are crucial if we are to understand the evolutionary and environmental factors responsible for the diversity of TLs and levels of telomerase expression observed among species [13,14]. TL has been proposed as an important biomarker within evolutionary ecology and animal welfare because it may reflect an individual’s cumulative experience of environmental stress and investment in growth or reproduction [17,18,19] This leads to the expectation that shorter TL will predict raised subsequent mortality risk, without telomeres necessarily being causally involved in death, due to increased somatic damage associated with environmental stress and reduced investment in somatic repair [17,19]. We use meta-regression 2 analyses to investigate potential sources of variation in this association across studies including methodology, life stage at sampling, follow-up period and sex
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