Abstract
ABSTRACTEarly life conditions can affect individuals for life, with harsh developmental conditions resulting in lower fitness, but the underlying mechanisms are not well understood. We hypothesized that immune function may be part of the underlying mechanism, when harsh developmental conditions result in less effective immune function. We tested this hypothesis by comparing innate immune function between zebra finches (Taeniopygia guttata) in adulthood (n=230; age 108–749 days) that were reared in either small or large broods. We used this experimental background to follow up our earlier finding that finches reared in large broods have a shorter lifespan. To render a broad overview of innate immune function, we used an array of six measures: bacterial killing capacity, hemagglutination, hemolysis, haptoglobin, nitric oxide and ovotransferrin. We found no convincing evidence for effects of natal brood size on any of the six measures of innate immune function. This raised the question whether the origin of variation in immune function was genetic, and we therefore estimated heritabilities using animal models. However, we found heritability estimates to be low (range 0.04–0.11) for all measured immune variables, suggesting variation in innate immune function can largely be attributed to environmental effects independent of early-life conditions as modified by natal brood size.
Highlights
IntroductionThe early developmental period is a sensitive life stage, and earlylife conditions can have strong effects on fitness (Briga et al, 2017; Reid et al, 2003; Saino et al, 2018; Van De Pol et al, 2006)
The early developmental period is a sensitive life stage, and earlylife conditions can have strong effects on fitness (Briga et al, 2017; Reid et al, 2003; Saino et al, 2018; Van De Pol et al, 2006). Such effects are mediated through long-term phenotypic effects of early-life conditions, shaping subsequent behavior, physiology and morphology
We found no clear evidence for any effects of early developmental condition on innate immune function in adulthood
Summary
The early developmental period is a sensitive life stage, and earlylife conditions can have strong effects on fitness (Briga et al, 2017; Reid et al, 2003; Saino et al, 2018; Van De Pol et al, 2006). Such effects are mediated through long-term phenotypic effects of early-life conditions, shaping subsequent behavior, physiology and morphology. Manipulation of natal brood size, which typically affects growth, has long-term phenotypic effects on physiology Received 17 December 2020; Accepted 20 April 2021 to cause a shortening of adult lifespan (Briga et al, 2017; De Kogel, 1997), but the mechanisms causing this effect remain to be elucidated
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