Journal Article
Embryonic exposure to maternal testosterone influences age-specific mortality patterns in a captive passerine bird
Schwabl, H., Holmes, D., Strasser, R., Scheuerlein, A.
Age, 34:1, 87–94 (2012)
Abstract
Hormones are potent mediators of developmental
programming and maternal epigenetic effects.
In vertebrates, developmental exposure to maternal
androgen hormones has been shown to impact multiple
behavioral and physiological traits of progeny, but the
possible consequences of this early exposure in
terms of aging-related changes in mortality and fitness
remain largely unexplored. Avian eggs naturally contain
variable doses of maternal hormones—in particular,
androgens—which have documented effects on embryo
growth and differentiation as well as adult behavior and
physiology. Here, we report that injections of a
physiological dose of testosterone (T) into yolks of
freshly laid eggs of a small, seasonally breeding
songbird, the house sparrow (Passer domesticus),
increased survivorship in a semi-natural aviary environment.
In addition, survival effects of developmental
T exposure were sex-dependent, with males generally
having a higher risk of death. Separate analyses for
young birds in their first year of life (from hatching up
to the first reproductive period the following calendar
year) and in adulthood (after the first breeding season)
showed similar effects. For first-year birds, mortality
risk was higher during the winter than during the period
after fledging; for adults, mortality risk was higher
during the reproductive than the non-reproductive phase
(post-breeding molt and winter). T treatment did not
affect nestling body mass, but resulted in higher body
mass at 3–4months of age; T and body mass at this age
interacted to influence mortality risk. Embryonic exposure
to maternal testosterone may result in lower adult
mortality by modifying intrinsic physiological processes
involved in health or aging over the lifespan of adult
birds.
Keywords: early childhood, endocrine system, survival