Born without a Silver Spoon: A Review of the Causes and Consequences of Adversity during Early Life

Abstract

A huge amount of research attention has focused on the evolution of life histories but most research focuses on dominant individuals that acquire a disproportionate level of reproductive success, whilst the life histories and reproductive tactics of subordinate individuals has received less attention. Here, we review the links between early life adversity and performance during adulthood in birds, and highlight instances in which subordinate individuals out-perform dominant conspecifics. Subordinate individuals are those from broods raised under high risk of predation, with low availability of food and/or with many parasites. Meanwhile, the broods of many species hatch or are born asynchronously and mitigation of the asynchrony is generally lacking from variation in maternal effects such as egg size and hormone deposition or genetic effects such as offspring sex or parentage. Subordinate individuals employ patterns of differential growth to attempt to mitigate the adversity they experience during early life, yet they overwhelmingly fail to overcome their initial handicap. In terms of surviving through to adulthood, subordinate individuals employ other “suboptimal” tactics, such as adaptively timing foraging behaviours to avoid dominant individuals. During adulthood, meanwhile, subordinate individuals rely on “suboptimal” tactics, such as adaptive dispersal behaviours and competing for partners at optimal times, because they represent the best options available to them to acquire copulations whenever possible. We conclude that there is a gap in knowledge for direct links between early life adversity and subordination during adulthood, meaning that further research should test for links. There are instances, however, where subordinate individuals employ “suboptimal” tactics that allow them to outperform dominant conspecifics during adulthood.

Differential effects of early life adversity on male and female rhesus macaque lifespan

“…Observing early life adversity effects on a provisioned primate population with no seasonal changes in food availability also raises important questions regarding the role that calorie deficit early in life has as a driver of developmental constrains that result in poor adult health and survival. Finally, other adaptive behaviors (e.g., foraging timing; Mainwaring et al., 2023 ) must also be addressed to fully understand how affected individuals may mitigate the adversity they experienced early in life that likely result in the different observed responses across primate populations.…”

“…and survival. Finally, other adaptive behaviors (e.g., foraging timing;Mainwaring et al, 2023) must also be addressed to fully understand how affected individuals may mitigate the adversity they experienced early in life that likely result in the different observed responses across primate populations. AUTH O R CO NTR I B UTI O N S Stephanie J. Gonzalez: Conceptualization (equal); data curation (lead); formal analysis (lead); investigation (equal); methodology (equal); validation (equal); visualization (equal); writing -original draft (equal); writing -review and editing (equal).…”

Differential effects of early life adversity on male and female rhesus macaque lifespan

“…Incorporating this would further our understanding of the observed differential effects of early life adversity in male and female primates. Other adaptive behaviors (e.g., foraging timing; Mainwaring et al, 2023) must also be addressed to fully understand how disadvantaged individuals may mitigate the adversity they experienced early in life. Finally, our study highlights the need for studies addressing the effects of early life adversity across multiple life stages.…”

Juvenile survival of little owls decreases with snow cover

“…Because body mass and size were highly correlated, and the variables age and body size did not affect survival in preliminary explorations, we retained the most parsimonious combination of variables (Hooten & Hobbs, 2015 ), and neither age nor size was retained in our survival model. We fitted three models to include the variables body mass and supplementary feeding in three alternative model formulations: either by affecting survival only in the immediate post‐fledging period (Perrig et al., 2017 ) or by allowing body mass and supplementary feeding to affect survival in every season over the first year of life (Catitti et al., 2022 ; Mainwaring et al., 2023 ; Nägeli et al., 2022 ).…”