Interplays between pre- and post-natal environments affect early-life mortality, body mass and telomere dynamics in the wild

Abstract

Early-life conditions are crucial determinants of phenotype and fitness. The effects of pre- and postnatal conditions on fitness prospects have been widely studied but their interactive effects have received less attention. In birds, asynchronous hatching creates challenging developmental conditions for the last-hatched chicks, but differential allocation in last-laid eggs might help to compensate this initial handicap. The relative importance and potential interaction between pre- and post-hatching developmental conditions for different fitness components remains mostly unknown. We manipulated hatching order in wild pied flycatchers (Ficedula hypoleuca), creating three groups: Natural asynchrony (last-laid eggs hatching last), Reversed asynchrony (last-laid eggs hatching first) and Hatching synchrony (all eggs hatching at once). We examined the effects of these manipulations on early-life survival, growth and telomere length, a potential cellular biomarker of fitness prospects. Mortality was mostly affected by hatching order, with last-hatched chicks being more likely to die. Early-life telomere dynamics and growth were influenced by the interplays between laying and hatching order. Last-laid but first-hatched chicks were heavier but had shorter telomeres 5 days after hatching than their siblings, indicating rapid early growth with potential adverse consequences on telomere length. Synchronous chicks did not suffer any apparent cost of hatching synchronously. Impaired phenotypes only occurred when reversing the natural hatching order (i.e. developmental mismatch), suggesting that maternal investment in last-laid eggs might indeed counterbalance the initial handicap of last-hatched chicks. Our experimental study thus highlights that potential interplays between pre- and post-natal environments are likely to shape fitness prospects in the wild.

The tarnished silver spoon? Trade‐off between prenatal growth and telomere length in wild boar

“…Piglet mortality in domestic pigs, Sus scrofa domesticus , is the highest within the first three days after birth and most piglets die from crushing or starvation (eg Dyck & Swierstra, 1987 ; Edwards, 2002 ). The observed increase in RTL during postnatal development indicates that the piglets in our study were able to invest into both growth and telomere restoration and supports our hypothesis that high amount of available food can provide the possibility to compensate telomere loss (eg Kärkkäinen et al, 2021 ). Previous studies suggested that higher postnatal growth rates lead to more telomere attrition if growth is not accompanied by an increased supply of nutrition to buffer the oxidative damage (eg Vedder et al, 2018 ).…”

Within‐individual repeatability in telomere length: A meta‐analysis in nonmammalian vertebrates

“…The within‐individual repeatability ( R) of measurements over time is a key requirement to identify the dynamics of variables and the factors driving these dynamics. Telomere length changes over time and this change is known to be affected by various factors, for example, pre‐ and postnatal environmental conditions (Kärkkäinen et al, 2021; Stier et al, 2020), stress exposure (Chatelain et al, 2020), and reproductive effort (Reichert, Stier, et al, 2014). Yet, to link a single telomere measurement to past environmental conditions or future performances (e.g., following reproductive success), telomere length also needs to be repeatable to some extent.…”

Within-individual repeatability in telomere length: a meta-analysis in non-mammalian vertebrates

“…Telomere length changes over time and this change is known to be affected by various factors, e.g. pre-and postnatal environmental conditions (Kärkkäinen, Teerikorpi, Schuett, Stier, & Laaksonen, 2021;Stier et al, 2020;Stier, Metcalfe, & Monaghan, 2020), stress exposure (Chatelain et al, 2020), and reproductive effort ). Yet, to be informative of future performances (e.g.…”