The impact of development on patterns of nutrient limitation

1. Development is often accompanied by major changes in an organism’s functioning and in the way it interacts with its environment. We consider how developmental events such as allocation changes at maturity, ontogenetic diet shift or metamor- phosis may affect the likelihood and nature of nutrient limitation and explore the consequences of these changes in nutrient limitation for individual life history and patterns of biomass production.
2. To this purpose, we develop a general model for individual growth and reproduc- tion that is based on the assumption that biomass production and metabolism re- quire several nutrients and that individuals may require them in different proportion at different stages of their lives.
3. We parameterize this model for Daphnia based on its physiological requirements for carbon (C) and phosphorus (P). Growth and reproduction have different nutri- ent requirements, and this affects the likelihood of C vs. P limitation of differently sized individuals. This translates into a size-dependent threshold elemental ratio (TER), with a difference of up to twofold between juveniles and adults, a differ- ence comparable to measured interspecific differences.
4. The main implications of these findings are that, at the population level, co-limita- tion of biomass production by several nutrients is likely to occur under a wide range of food qualities. In addition, different regimes of nutrient limitation strongly influence the relative difference in biomass production of differently sized indi- viduals, which has been shown to be a major driver of population and community dynamics. Our results point to development as a key determinant of a population’s response to food quality.