Macquarie University
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Environmentally induced variation in DNA methylation and embryonic heart rate in Australian birds

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posted on 2022-03-28, 22:31 authored by Elizabeth L. Sheldon
The environment is profound in its ability to influence phenotypic variation, and this is a necessary condition for integrating the developing organism into its particular habitat. While phenotypic plasticity is well engrained in ecological research, the underlying processes that mediate its effects remain unclear. Recently, epigenetic and metabolic mechanisms have been proposed to provide an avenue through which early environmental conditions can modulate phenotypic variation. However, before these mechanisms can be implicated in translating environmental effects to the phenotype, it must first be clarified whether epigenetic and metabolic processes are sensitive to environmental variation at all. Here, I examined how DNA methylation and metabolic rate are affected by various abiotic and biotic stimuli in two species of Australian birds. I used MS-AFLP to examine population-wide, and condition dependent patterns of DNA methylation in invasive house sparrows (Passer domesticus) and zebra finches (Taeniopygia guttata), and measured embryonic heart rate (a proxy for metabolic rate) in wild, native zebra finches, to examine environmental effects on metabolism, and the behavioural and developmental consequences of this. The patterns of DNA methylation that were observed in my thesis support the potential for epigenetic marks to respond to prevailing environmental conditions (such as habitat, brood size, invasion history and temperature). Embryonic heart rate measures were also found to be extremely sensitive to a range of environmental stimuli, notably changing in response to temperature and conspecific vocalisations. Embryonic heart rate also correlated with pre-natal developmental rate, however was unrelated to variation in nestling activity levels. Together, the environmentally induced changes described in my thesis support a role for epigenetic and metabolic mechanisms to translate environmental effects to ecologically relevant phenotypic variation. Such phenotypic plasticity could be particularly important for wild populations facing unpredictable and rapid environmental changes.


Table of Contents

Chapter One. General introduction -- Chapter Two. Epigenetic variation across multiple introduction events in the invasive Australian house sparrow population -- Chapter Three. Brood size influences genome-wide DNA methylation levels in wild zebra finches (Taeniopygia guttata) -- Chapter Four. The effects of developmental temperature on DNA methylation in captive zebra finches (Taeniopygia guttata) -- Chapter Five. Measuring the embryonic heart rate of wild birds : an opportunity to take the pulse on early development -- Chapter Six. Zebra finch (Taeniopygia guttata) embryos show a cardiac response to conspecific but not heterospecific calls; however they do not discriminate between different calls within their own species -- Chapter Seven. Embryonic heart rate is associated with pre-natal development rate but not post-natal activity levels or growth rates in the zebra finch (Taeniopygia guttata) -- Chapter Eight. General discussion -- Conclusion -- Appendix.


Includes bibliographical references Thesis by publication.

Awarding Institution

Macquarie University

Degree Type

Thesis PhD


PhD, Macquarie University, Faculty of Science and Engineering, Department of Biological Sciences

Department, Centre or School

Department of Biological Sciences

Year of Award


Principal Supervisor

Simon Griffith


Copyright Elizabeth. L. Sheldon 2017. Copyright disclaimer:






1 online resource (232 pages) colour illustrations, colour portraits

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