Oxidative shielding and the cost of reproduction in the blue tit Cyanistes caeruleus
Walter, Miranda Alicia Rosanna
Date: 20 October 2017
Publisher
University of Exeter
Degree Title
MbyRes in Biological Sciences
Abstract
The cost of reproduction is considered to be a cornerstone of life history theory.
However, the physiological mechanism that underpins the cost of
reproductionremains unclear. Recently, considerable interest has been given to
oxidative stress as a functional mediator of the cost of reproduction. Empirical
studies aiming to test ...
The cost of reproduction is considered to be a cornerstone of life history theory.
However, the physiological mechanism that underpins the cost of
reproductionremains unclear. Recently, considerable interest has been given to
oxidative stress as a functional mediator of the cost of reproduction. Empirical
studies aiming to test the oxidative cost of reproduction have so far yielded
equivocal results. Recently, a new hypothesis was presented, offering a
framework for future study design. The ‘oxidative shielding’ hypothesis
proposes that the cost of reproduction is mediated by dual impacts of
maternally-derived oxidative damage on mothers and offspring, and that
mothers may be selected to shield offspring from such damage transmitted
during reproduction. In this landscape-scale study on populations of wild blue
tits Cyanistes caeruleus I have tested the oxidative cost of reproduction within
the framework proposed by the ‘oxidative shielding’ hypothesis. I present data
indicating a longitudinal change in oxidative status from pre-laying to clutch
completion suggestive of oxidative shielding within breeding females.
Additionally, oxidative stress in females is seen to impose a constraint on clutch
size, and the transmission of oxidative damage from mother to egg was found
to have negative implications for offspring survival. Lastly, examination of the
association between oxidative stress and antioxidants within yolk and plasma
suggests a protective role of vitamin E in yolk, but no association with oxidative
damage in plasma. These findings provide preliminary support for the ‘oxidative
shielding’ hypothesis and highlight areas of focus for future research into the
oxidative cost of reproduction.
MbyRes Dissertations
Doctoral College
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