Early growth conditions, phenotypic development and environmental change

Abstract

Phenotypic development is the result of a complex interplay involving the organism's own genetic make-up and the environment it experiences during development. The latter encompasses not just the current environment, but also indirect, and sometimes lagged, components that result from environmental effects on its parents that are transmitted to their developing offspring in various ways and at various stages. These environmental effects can simply constrain development, for example, where poor maternal condition gives rise to poorly provisioned, low-quality offspring. However, it is also possible that environmental circumstances during development shape the offspring phenotype in such a way as to better prepare it for the environmental conditions it is most likely to encounter during its life. Studying the extent to which direct and indirect developmental responses to environmental effects are adaptive requires clear elucidation of hypotheses and careful experimental manipulations. In this paper, I outline how the different paradigms applied in this field relate to each other, the main predictions that they produce and the kinds of experimental data needed to distinguish among competing hypotheses. I focus on birds in particular, but the theories discussed are not taxon specific. Environmental influences on phenotypic development are likely to be mediated, in part at least, by endocrine systems. I examine evidence from mechanistic and functional avian studies and highlight the general areas where we lack key information.

Effects of early developmental conditions on innate immunity are only evident under favourable adult conditions in zebra finches

“…Gluckman and Hanson 2004;Lindström 1999;Lummaa and CluttonBrock 2002;Metcalfe and Monaghan 2001). Long-term consequences of early developmental conditions have, however, been found to vary with the quality of the adult environment in opposing ways (reviewed in Monaghan 2008). First, it has been demonstrated that nestlings raised under poor conditions suffer a suboptimal development and experience negative effects irrespective of the quality of the adult environment (Grafen 1988;Monaghan 2008).…”

“…Long-term consequences of early developmental conditions have, however, been found to vary with the quality of the adult environment in opposing ways (reviewed in Monaghan 2008). First, it has been demonstrated that nestlings raised under poor conditions suffer a suboptimal development and experience negative effects irrespective of the quality of the adult environment (Grafen 1988;Monaghan 2008). Second, several studies found that long-term effects of developmental stress remain masked under favourable adult conditions as physiological responses are not affected by an individual's quality (e.g.…”

“…Third, individuals developing under unfavourable circumstances may cope better with poor conditions during adulthood because of the similarity between early and later environments. If this is the case, a reverse pattern can be expected when adult conditions are more favourable, as organisms raised in poor environments are not developmentally adapted to more favourable ambient conditions (Monaghan 2008).…”

Effects of rearing conditions on natal dispersal processes in a long‐lived predator bird

“…In fact, several studies of mammals and birds have shown that parents cannot fully compensate for the increased energetic requirement of an enlarged brood (Monaghan, 2008; Rémy et al., 2011). Bonelli’s eagles usually lay one or two eggs (Real, 1991), so females have to face a trade‐off between forming one or two eggs at the time of egg formation.…”

“…We considered past productivity, the number of chicks in each nest, and their interactions as explanatory variables. The number of reared chicks was included because it has been shown to have an effect on the body condition of nestlings in several long‐lived bird species (Monaghan, 2008). …”