Telomere length reveals cumulative individual and transgenerational inbreeding effects in a passerine bird

Inbreeding results in more homozygous offspring that should suffer reduced fitness, but it can be difficult to quantify these costs for several reasons. First, inbreeding depression may vary with ecological or physiological stress and only be detectable over long time periods. Second, parental homozygosity may indirectly affect offspring fitness, thus confounding analyses that consider offspring homozygosity alone. Finally, measurement of inbreeding coefficients, survival and reproductive success may often be too crude to detect inbreeding costs in wild populations. Telomere length provides a more precise measure of somatic costs, predicts survival in many species and should reflect differences in somatic condition that result from varying ability to cope with environmental stressors. We studied relative telomere length in a wild population of Seychelles warblers (Acrocephalus sechellensis) to assess the lifelong relationship between individual homozygosity, which reflects genome-wide inbreeding in this species, and telomere length. In juveniles, individual homozygosity was negatively associated with telomere length in poor seasons. In adults, individual homozygosity was consistently negatively related to telomere length, suggesting the accumulation of inbreeding depression during life. Maternal homozygosity also negatively predicted offspring telomere length. Our results show that somatic inbreeding costs are environmentally dependent at certain life stages but may accumulate throughout life.</p

Exploration is dependent on reproductive state, not social state

Personality is an intriguing phenomenon in populations because it constrains behavioural flexibility. One theory suggests that personality could be generated and maintained if dependent on asset protection. It is predicted that trade–offs with fitness expectations and survival probability encourage consistent behavioural differences among individuals (personality). Although not mutually exclusive, the social niche specialisation hypothesis suggests that a group of individuals that repeatedly interact will develop personality to avoid costly social conflict. The point at which behavioural consistency originates in the social niche hypothesis is still unclear, with predictions for development after a change in social status. In the facultative cooperatively breeding Seychelles warbler (Acrocephalus sechellensis), residing on Cousin Island, breeding vacancies are limited and this forces individuals into different social roles. We used this system to test whether reproductive and social state predicted among–individual differences in exploration. We had two predictions. Firstly, that an individual’s start in life can predict personality, whereby young individuals with a good start to life (associated with early age reproduction and earlier onset survival senescence) are fast explorers, suggesting reproductive state–dependence. Secondly, that an individual’s social status can predict personality, whereby dominant individuals will be fast explorers suggesting that the behaviour is social state–dependent. Neither of the behaviours were associated with social state and social state did not affect behavioural consistency. However, novel object exploration was associated with a proxy of reproductive state. Our results provide further support for state being a mechanism for generating individual differences in behaviour

Data from: Repeatable and heritable behavioural variation in a wild cooperative breeder

Quantifying consistent differences in behaviour among individuals is vital to understanding the ecological and evolutionary significance of animal personality. To quantify personality, the phenotypic variation of a behavioural trait is partitioned to assess how it varies among individuals, which is also known as repeatability. If pedigree data are available, the phenotypic variation can then be further partitioned to estimate the additive genetic variance and heritability. Assessing the repeatability and heritability of personality traits therefore allows for a better understanding of what natural selection can act upon, enabling evolution. In a natural population of facultative cooperatively breeding Seychelles warbler (Acrocephalus sechellensis) on Cousin Island, a lack of breeding vacancies forces individuals into different life-history strategies, and these differences in reproductive state could generate behavioural differences among individuals in the population. We used this population to estimate the repeatability of 4 behavioural traits (novel environment exploration, novel object exploration, obstinacy/struggle rate, and escape response), and narrow-sense heritability (of behavior, h2B; behavior minus observer variance; and personality), and evolvability, of the repeatable behavioural traits. We also tested for an among-individual correlation between the repeatable traits. We found that, compared to estimates in other study species, the exploratory behaviours were moderately repeatable (0.23–0.37), there was a positive among-individual correlation (0.51) between novel environment and novel object exploration, and that novel environment exploration was moderately heritable (0.17; h2B was low as it includes observer variance). This study further clarifies the additive genetic variance available for selection to act upon in this cooperatively breeding bird. The data package contains one dataset: - Data for analysis of personality in the Seychelles warbler

Primary data Bebbington et al. 2017 PNAS.xlsx

Primary data used to produce the results reported in the study. Each tab contains the data relating to one of the analyses

Replication Data for: Early-life conditions impact juvenile telomere length, but do not predict later life-history strategies or fitness in a wild vertebrate

This dataset consists of two data files (Excel) and corresponding R-scripts to process the data

Additional file 3 of Immunogenetic variation shapes the gut microbiome in a natural vertebrate population

The identity of 19 amplicon sequencing variants (ASVs) identified in the negative extraction controls. A taxonomic breakdown and the number of reads associated with each ASV is provided. ASVs were either filtered from the dataset before further analysis or retained. In the second tab is a detailed breakdown of number of reads with each ASV present in each sample, along with whether it is a negative control or faecal sample, and whether it was sequenced in the 1st, 2nd, or 3rd sequencing run

Additional file 4 of Immunogenetic variation shapes the gut microbiome in a natural vertebrate population

Additional file 3. Differentially abundant ASVs (Padj &lt; 0.01) in the gut microbiomes of Seychelles warblers, according to the presence/absence of the MHC-I alleles A) Ase-ua7 B) Ase-ua11 or C) Ase-ua1/10. Differential ASV abundance was assessed using negative binomial Wald tests and P values were adjusted using the Benjamini and Hochberg false-discovery rate correction with a significance cut-off of P &lt; 0.01. ASVs shown with a log2-fold change greater than zero are significantly more abundant in individuals without this allele and ASVs with a log2 fold change smaller than zero are significantly more abundant in individuals with a copy of this allele

Data from: Sex-dependent effects of parental age on offspring fitness in a cooperatively breeding bird

Parental age can have considerable effects on offspring phenotypes and health. However, intergenerational effects may also have longer-term effects on offspring fitness. Few studies have investigated parental age effects on offspring fitness in natural populations while also testing for sex- and environment-specific effects. Further, longitudinal parental age effects may be masked by population-level processes such as the selective disappearance of poor-quality individuals. Here, we used multi-generational data collected on individually marked Seychelles warblers (Acrocephalus sechellensis) to investigate the impact of maternal and paternal age on offspring lifespan and lifetime reproductive success. We found negative effects of maternal age on female offspring lifespan and lifetime reproductive success, which were driven by within-mother effects. There was no difference in annual reproductive output of females born to older versus younger mothers, suggesting that the differences in offspring lifetime reproductive success were driven by effects on offspring lifespan. In contrast, there was no association between paternal age and female offspring lifespan or either maternal or paternal age and male offspring lifespan. Lifetime reproductive success, but not annual reproductive success, of male offspring increased with maternal age, but this was driven by between-mother effects. No paternal age effects were found on female offspring's lifetime reproductive success but there was a positive between-father effect on male offspring's lifetime reproductive success. We did not find strong evidence for environment-dependent parental age effects. Our study provides evidence for parental age effects on the lifetime fitness of offspring and shows that such effects can be sex-dependent. These results add to the growing literature indicating the importance of intergenerational effects on long-term offspring performance and highlight that these effects can be an important driver of variation in longevity and fitness in the wild