Telomere heritability and parental age at conception effects in a wild avian population

Abstract

Individual variation in telomere length is predictive of health and mortality risk across a range of species. However, the relative influence of environmental and genetic variation on individual telomere length in wild populations remains poorly understood. Heritability of telomere length has primarily been calculated using parent–offspring regression which can be confounded by shared environments. To control for confounding variables, quantitative genetic “animal models” can be used, but few studies have applied animal models in wild populations. Furthermore, parental age at conception may also influence offspring telomere length, but most studies have been cross‐sectional. We investigated within‐ and between‐parental age at conception effects and heritability of telomere length in the Seychelles warbler using measures from birds caught over 20 years and a multigenerational pedigree. We found a weak negative within‐paternal age at conception effect (as fathers aged, their offspring had shorter telomeres) and a weak positive between‐maternal age at conception effect (females that survived to older ages had offspring with longer telomeres). Animal models provided evidence that heritability and evolvability of telomere length were low in this population, and that variation in telomere length was not driven by early‐life effects of hatch period or parental identities. Quantitative polymerase chain reaction plate had a large influence on telomere length variation and not accounting for it in the models would have underestimated heritability. Our study illustrates the need to include and account for technical variation in order to accurately estimate heritability, as well as other environmental effects, on telomere length in natural populations.

Contemporary evolution of the innate immune receptor gene TLR3 in an isolated vertebrate population

“…Individuals were genotyped at 30 polymorphic microsatellite loci (Richardson et al, 2001). Parentage assignment was carried out using MasterBayes 2.52 (Hadfield et al, 2006); for full details see Sparks et al (2021). Parentage assignment was conducted for 1966 offspring that hatched between 1993-2018, with 89% of fathers and 86% of mothers assigned at ≥80% accuracy.…”

“…Standardised individual and maternal microsatellite heterozygosity ( H s ) was calculated using the R package genhet 3.1 (Coulon, 2010). Two of the microsatellite loci were excluded from this heterozygosity analysis due to pooled alleles (see Sparks et al, 2021). Variation at exon 3 of the MHC class I loci (MHC‐I) had previously been screened in individuals from Cousin (1148 individuals hatched between 1992–2009) (Richardson & Westerdahl, 2003; Wright, Spurgin, et al, 2014).…”

“…Pathogens can have considerable negative impact on the survival and reproductive success of individuals (Daszak et al, 2000), and are strong drivers of evolutionary change in natural populations (Haldane, 1992). Consequently, immunogenetic locii.e., those involved in the detection and combating of pathogens -are excellent candidates in which to investigate the evolutionary forces underlying the maintenance of genetic variation (Croze et al, 2016;Sommer, 2005). Indeed, pathogen-mediated selection is thought to be a key driver of balancing selection (Spurgin & Richardson, 2010).…”

Gut microbiome composition, not alpha diversity, is associated with survival in a natural vertebrate population

“…This stable population consists of ca 320 adult individuals [41], nearly all of which (> 96%) have been ringed with a unique combination of a British Trust for Ornithology (BTO) metal ring and three plastic colour rings [42]. Seychelles warblers are long-lived, with a median life expectancy at fledgling of 5.5 years and a maximum recorded lifespan of 19 years [43,44].…”

“…A blood sample was taken via brachial venipuncture and DNA was extracted using the DNeasy Blood and Tissue kit (Qiagen, Crawley, UK) according to the manufacturer's instructions. Molecular sexing was subsequently carried out using a PCR-based method [44,49]. Each individual was classified into one of the following age classes based on a combination of hatch date, behavioural observations, and eye-colour, which changes from grey in fledglings to red-brown in adult individuals [47]: nestling (in the nest), fledgling (1-3 months), old fledgling (3-5 months, and less reliant on parents for food), subadults (5-12 months), or adults (>12 months).…”