Dynamic changes in DNA methylation during postnatal development in zebra finches <i>Taeniopygia guttata</i> exposed to different temperatures

Hurley

Griffith

2021

Ibis

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In birds, ambient temperature can influence adult incubation behaviour, energy budget, egg temperature and embryonic development, with downstream effects on offspring survival. Surprisingly, experimental manipulations of the whole nesting environment to test causes and consequences of variation in incubation pattern, energy balance, egg temperature and the duration of development are lacking to date. Here, we bred pairs of Zebra Finches Taeniopygia guttata under controlled conditions at 18 and 30 °C and measured clutch size, temperature, hatching success, parental attentiveness and the length of the embryonic period. We found that when breeding at the higher temperature, males, but not females, increased the number of incubation bouts on the nest. Instead, females, but not males, reduced their attentiveness towards the clutch overall. Eggs showed no temperature differences between the two treatments and bigger clutches experienced lower temperatures. This suggests that parental behaviour may buffer the effect of ambient conditions on the thermal profile of eggs, including species with high rates of parental attentiveness. Warmer conditions yielded higher hatching rates but did not cause measurable differences in the length of embryonic development. Still, smaller clutches hatched earlier in accordance with the higher temperature experienced. Additionally, we used data from the literature to calculate parental energy expenditure and demonstrate that this was substantially different across the two treatments, although predicted energy savings from reduced attentiveness at 30 °C appeared negligible. These results suggest that when food is available, ambient temperature and not energy trade‐offs may explain variation in incubation behaviour.

Section: Discussionmentioning

confidence: 99%

Higher experimental ambient temperature decreases female incubation attentiveness in Zebra Finches (Taeniopygia guttata) and lower effort yields negligible energy savings

Hurley

Griffith

2021

Ibis

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“…Contrary to other studies (Stier et al, 2020;Fitzpatrick et al, 2019), we did not find an effect of ambient temperature on telomere length or telomere length changes across development. Temperature has been shown to effect within individual changes in DNAm (Sheldon et al, 2020) and telomere length (Stier et al 2020;Fitzpatrick et al 2019) however, it is unclear if temperature effects these DNA modifications comparably. The temperatures (average daily maximum of 27.6 o C) in our study may not have been 'stressful' enough to impact telomere dynamics, and indeed temperature has not affected telomere length in studies on other taxa (McLennan et al, 2018;Boonekamp et al, 2020).…”

Section: Discussionmentioning

confidence: 99%

“…DNAm and telomere length are highly responsive to environmental cues (Feil & Fraga, 2012;Monaghan, 2014), particularly during early life (Watson, Bolton & Monaghan, 2019;Boonekamp et al, 2014). For example, studies have detected associations between DNAm or telomere length and clutch/brood size (Noguera & Velando, 2020;Jimeno, Hau, Gomez-Diaz, & Verhulst, 2019;Sheldon, Schrey, Ragsdale & Griffith 2018;Nettle et al, 2016;Reichert et al, 2014;Costanzo et al, 2016;Boonekamp et al, 2014); ambient temperature (Stier, Metcalfe & Monaghan, 2020;Sheldon, Schrey, Hurley, & Griffith, 2020;Yan et al, 2015); and body size/growth rate (Young et al, 2017;Vedder et al, 2018). It is therefore important to account for these influences when testing the association between DNAm and telomere length.…”

Section: Introductionmentioning

confidence: 99%

Associations between DNA methylation and telomere length during early life: insight from wild zebra finches (Taeniopygia guttata)

Sheldon

Boner

et al. 2021

Preprint

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Telomere length and DNA methylation (DNAm) are two promising biomarkers of biological age. Environmental factors and life history traits are known to affect variation in both these biomarkers, especially during early life, yet surprisingly little is known about their reciprocal association. Here, we present the first study on a natural population to explore how variation in DNAm, growth rate and early-life conditions are associated with telomere length changes during development. We tested these associations by collecting data from wild, nestling zebra finches in the Australian desert. We found that increases in the level of DNAm were negatively correlated with telomere length changes across early life. We also confirm previously documented effects of post hatch growth rate and clutch size on telomere length in a natural ecological context for a species that has been extensively studied in the laboratory. However, we did not detect any effect of ambient temperature during developmental on telomere dynamics. We also found that the absolute telomere length of wild zebra finches, measured using the in-gel TRF method, was similar to that of captive birds. Our findings highlight exciting new opportunities to link and disentangle potential relationships between environmental, epigenetic and telomere length dynamics during early life.

“…Furthermore, nest temperatures have been found to exceed 40 • C regularly in the wild during active breeding [51], and variation in ambient heat across developing Zebra Finch broods has been found to influence body size [52], stress physiology [53], and the level of DNA methylation [54]. These effects may result from the effect of ambient heat exposure on either embryos or nestlings, both sensitive stages of development.…”

Section: Climatic Extremes During Breeding and Developmentmentioning

confidence: 99%

The Ecology of the Zebra Finch Makes It a Great Laboratory Model but an Outlier amongst Passerine Birds

Griffith

Hurley

et al. 2021

Birds

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Zebra Finches have become the most widely researched bird species outside of those used in agricultural production. Their adoption as the avian model of choice is largely down to a number of characteristics that make them easy to obtain and use in captivity. The main point of our paper is that the very characteristics that make the Zebra Finch a highly amenable laboratory model species mean that it is by definition different from many other passerine birds, and therefore not a good general model for many research areas. The Zebra Finch is likely to be particularly resilient to the effects of stress early in life, and is likely to show great flexibility in dealing with a wide variety of conditions later in life. Whilst it is tempting for researchers to turn to species such as the Zebra Finch, that can be the focus of manipulative work in the laboratory, we caution that the findings of such studies may confound our understanding of general avian biology. The Zebra Finch will remain an excellent species for laboratory work, and our paper should help to direct and interpret future work in the laboratory and the field.