Biology subjects

Boonekamp, J. J.

Publications and source records attributed to Boonekamp, J. J..

6 recordsLinked to original sources

bioRxiv2026

Growing despite ectoparasite infection: sex-specific effects on telomere shortening in a free-living corvid

Ectoparasite infections during development are known to impact fitness-related traits, but their physiological costs in relation to sex or growth trade-offs are understudied. In birds, previous studies at the brood level have found costs of infection by blood-sucking ectoparasites in molecular biomarkers (i.e., increased telomere shortening). However, infection probability also varies with age, sex, or within broods. Whether such costs are age or sex-dependent is not well known, and disentangling these effects is of interest, because telomeres potentially reveal the long-term impact of infection. Here, we used 6-year-data from jackdaw nestlings (Coloeus monedula) to investigate individual level associations of infection by the fly (Carnus hemapterus) at two intermediate time points during development, with telomere dynamics over the nestling period. We evaluated (i), Carnus presence in relation to sex, brood size manipulation, body mass, and size, and (ii), how telomere shortening varied in relation to parasite presence and achieved growth. Early in development (day 10), flies were more prevalent on heavier nestlings, while later in development (day 20), they were more prevalent on smaller and lighter nestlings, suggesting different ectoparasite preference. Telomere loss was higher in female nestlings when exposed to parasites only on day 20, and in males, when they were heavy earlier in development. In conclusion, infection is a dynamic process, and ectoparasite effects may depend on the timing of infection and reveal sex-specific growth vs. self-maintenance trade-offs. Our study indicates a need to sample at multiple developmental stages when assessing host-parasite interactions and the physiological costs of infection.

evolutionary biology↗

bioRxiv2026

Parental age at reproduction accelerates offspring pace of life in Gryllus bimaculatus

Across invertebrates, it is widely known that older parents produce offspring with abbreviated lifespans (i.e., the Lansing effect). Yet the ecological and evolutionary ramifications of such nongenetic parental age effects remain unclear. Two demographic processes could culminate in a Lansing effect, with different fitness implications: (i) Later-conceived offspring may display greater mortality from conception, constraining fitness from birth. (ii) Alternatively, they may exhibit an increased age-specific mortality (i.e., accelerated senescence), with negative effects that manifest after maturity. If parental age accelerates offspring senescence without affecting initial mortality rate, then later-conceived offspring may maintain fitness by shifting to a faster pace-of-life. We exposed Gryllus bimaculatus parents to one of three experimental temperatures to generate environmental variation in parent mortality. Using a longitudinal within-parent study, we tested whether parental age influenced offspring longevity via increased initial mortality or accelerated senescence, and whether these effects depended on the parents thermal environment. Contrary to our predictions, we found no evidence that parental age reduced offspring longevity. Instead, parental age mediated offspring pace-of-life. Irrespective of the parents thermal environment, the earliest- and latest-conceived offspring were demographically distinct. Later-conceived offspring exhibited accelerated development, a smaller adult mass, and improved reproductive success. Unexpectedly, they also showed extended adult lifespans. This increased adult lifespan did not arise from reduced initial mortality, but from a delayed onset and slower progression of actuarial senescence. The slowed senescence in later-conceived offspring is unlikely to reflect a direct parental age effect, potentially arising indirectly through causal effects on adult size. Our results challenge the universality of the Lansing effect and contribute to a growing recognition that parental age has important life-history consequences. Accelerated life-histories in later-conceived offspring may be adaptive, enabling these individuals to compete over dwindling seasonal resources or overcome seasonal time constraints. Determining whether these demographic parental age effects accumulate across generations, or persist under natural environments, will be essential for establishing their ecological consequences and proximate role in the evolution of ageing. Open research statementData and code are not yet provided but will be made openly and freely available on request during the review process. Data will be uploaded to the Dryad data repository and code will be uploaded to Zenodo open repository on acceptance of the manuscript.

evolutionary biology↗

bioRxiv2022

Egg size effects on nestling mass in Jackdaws Corvus monedula: a cross-foster experiment

Variation in developmental conditions is known to affect fitness in later life, but the mechanisms underlying this relationship remain elusive. We previously found in jackdaws Corvus monedula that larger eggs resulted in larger nestlings up to fledging. Through a cross-foster experiment of complete clutches we tested whether this association can be attributed to egg size per se, or to more proficient parents producing larger eggs and larger nestlings, with the latter effect being more or less independent of egg size. Due to other manipulations post-hatching, we primarily investigated effects on nestling mass on day 5, which we show to predict survival until fledging. We introduce a new statistical approach to compare the competing hypotheses and conclude that 92% of the association between egg size and nestling mass is attributed to a direct effect of egg size, and that this relationship is not affected by variation in other parental quality. Intriguingly, the effect of egg size on day 5 nestling mass was steeper (1.7 g/cm3) than the effect of egg size on day 1 hatchling mass (0.7 g/cm3). Early growth is exponential, and the difference in effect size may therefore be explained by hatchlings from large eggs being further in their development at hatching. The direct effect of egg size on nestling mass raises the question what causes egg size variation in jackdaws.

ecology↗

bioRxiv2022

Does oxidative stress shorten telomeres in vivo? A meta-analysis

Telomere attrition is considered a hallmark of ageing. Untangling the proximate causes of telomere attrition may therefore reveal important aspects about the ageing process. In a landmark paper in 2002 Thomas von Zglinicki demonstrated that oxidative stress causes telomere attrition in cell culture. In the next 20 years, oxidative stress became firmly embedded into modern theories of ageing and telomere attrition. However, a recent surge of in vivo studies reveals an inconsistent pattern questioning the unequivocal role of oxidative stress in telomere dynamics, in living organisms. Here we report the results of the first formal meta-analysis on the association between oxidative stress and telomere dynamics in vivo, representing 37 studies, 4,834 individuals, and 18,590 correlational measurements. The overall correlation between oxidative stress markers and telomere dynamics was indistinguishable from zero. This result was independent of the type of oxidative stress marker, telomere dynamic, or taxonomic group. However, telomere measurement method affected the analysis with TRF but not qPCR-based studies showing a significant overall correlation. The correlation was more pronounced in short-lived species and during the adult life phase, when ageing becomes apparent. We then performed an additional meta-analysis of interventional studies (n=7) manipulating oxidative stress. This revealed a significant effect of treatment on telomere dynamics. Our findings indicate that oxidative stress may have a profound effect on telomere dynamics in living organisms fundamentally underpinning the process of ageing.

zoology↗

bioRxiv2020

High heritability of telomere length, but low evolvability, and no significant heritability of telomere shortening in wild jackdaws

Telomere length (TL) and shortening rate predict survival in many organisms. Evolutionary dynamics of TL in response to survival selection depend on the presence of genetic variation that selection can act upon. However, the amount of standing genetic variation is poorly known for both TL and TL shortening rate, and has not been studied for both traits in combination in a wild vertebrate. We used experimental (cross-fostering) and statistical (animal models) means to disentangle and estimate genetic and environmental contributions to TL variation in pedigreed free-living jackdaws (Corvus monedula). TL was measured twice early in life (age- and interval-standardized), when shortening is highest, using the high-precision TRF technique, adapted to exclude interstitial telomeric sequences. TL shortened significantly during the nestling phase (10.4 bp/day), was highly repeatable within individuals (R=0.97) and genetically correlated between the two ages (rG>0.99). Additive genetic effects explained the major part of TL variation between individuals, with heritability on average estimated at h2=0.74. Parent- offspring regressions yielded similar estimates for the sexes when accounting for changes in paternal TL over life. Cohort effects explained a small but significant part of TL variation. Heritable variation for telomere shortening was negligible. Despite the high heritability of TL, its evolvability, which scales the additive genetic variance by mean TL, was close to zero. Hence evolutionary change of TL is likely to be slow despite significant selection.

evolutionary biology↗

bioRxiv2018

Epigenetic inheritance of telomere length in wild birds

Telomere length (TL) predicts health and lifespan in humans and other organisms, making the identification of the causes of TL variation of interest. At conception, zygotes inherit genes that regulate TL during early development, but at the same time already express a phenotype, which is the TL of the parental gametes that formed the zygote. Whether the effect of gamete TL is transient or affects TL for life depends on the extent to which regulatory genes compensate for gamete TL variation during early development. A carry-over effect of parental TL, resulting in epigenetic inheritance, has been suggested to explain the observed relationship between parental age and offspring TL in humans and other species. However, reports of parental age effects are based on cross-sectional data, and age at reproduction has numerous confounds. Furthermore, parental age may affect offspring telomere dynamics between conception and sampling, which could also explain the paternal age effect. Using longitudinal telomere data of jackdaw parents and their chicks, we show that chicks hatched with shorter telomeres as individual fathers aged, whereas mother age had no effect. By cross-fostering eggs, we confirmed the paternal age effect to be independent of paternal care after conception. The epigenetic effect accounted for 34% of the variance in offspring TL that was explained by paternal telomere length; the remaining 66% we ascribe to a combination of environmental and additive genetic effects. Thus, our results strongly indicate epigenetic inheritance of TL, with potential consequences for offspring fitness prospects.\n\nSignificance statementTelomeres are DNA-protein structures at chromosome ends and their length predicts remaining lifespan in humans and other organisms. Variation in telomere length is thought to be largely of genetic origin, but telomere inheritance may be unusual because a fertilised cell already has a telomere length (most traits are first expressed later in life). Telomeres shorten with age, and, using long-term individual-based data of jackdaw families, we show that as fathers aged, they produced chicks with shorter telomeres. This shows that paternal telomere length directly affects offspring telomere length, i.e. is inherited genetically but without the involvement of genes. This is known as an epigenetic effect and explained a large part ([≥]34%) of the telomere resemblance between fathers and their offspring.

genetics↗