Genetic architecture and heritability of early-life telomere length in a
wild passerine
Abstract
Early-life telomere length (TL) is associated with fitness in a range of
organisms. Little is known about the genetic basis of variation in TL in
wild animal populations, but to understand the evolutionary and
ecological significance of TL it is important to quantify the relative
importance of genetic and environmental variation in TL. In this study,
we measured TL in 2746 house sparrow nestlings sampled across 20 years
and used an animal model to show that there is a small heritable
component of early-life TL (h2=0.04), but with a strong component of
maternal inheritance. Variation in TL among individuals was mainly
driven by environmental (year) variance, but also brood and parental
effects. We did not find evidence for a negative genetic correlation
underlying the observed negative phenotypic correlation between TL and
structural body size. Thus, TL may evolve independently of body size and
the negative phenotypic correlation is likely to be caused by
non-genetic environmental effects. We further used genome‐wide
association analysis to identify genomic regions associated with TL
variation. We identified several putative genes underlying TL variation;
these have been inferred to be involved in oxidative stress, cellular
growth, skeletal development, cell differentiation and tumorigenesis in
other species. Together, our results show that TL is a lowly heritable,
polygenic trait which is strongly affected by environmental conditions
in a free-living bird.