1. Romain Richard André de Roos
Population dynamics with multiple limiting nutrients: Life history mediated effects
Romain Richard
André de Roos

2. From individual development to population dynamics
Life history
& Co
Growth
Fecundity
Mortality
Feeding
Being fed upon
Population / community processes
Development
Physiology
Ingestion
Maturation
Allocation
Maintenance
Development is a major determinant of population dynamics

3. Dynamical effects of development
Makes competition between individual asymmetric: Individuals are not equally good at producing biomass
Population cycles
Alternative dynamical attractors
Coexistence
Biomass overcompensation
Catastrophic collapses
Facilitation
Allee effects
Juveniles
Adults
Total

4. Ecological stoichiometry
Individual experiencing different environment may be limited by different currency: energy vs mineral limitation
Focus on environmental and inter-specific variation
Intra-specific variation due to ontogenetic development

5. Mechanisms likely to induce changes in the limiting nutrient through development
Changes at maturation
Allometric scaling of body composition
Changes due to ontogenetic diet-shift / metamorphosis
Size-specific changes in physiological rates (ingestion, maintenance, maturation…)
How do multiple nutrient limitations affect individual life histories and what are the implications for ecological dynamics?

6. Individual model Differences in assimilation efficiency
Maintenance
Growth
Reproduction
Biomass
Overhead cost of growth
Overhead cost of reproduction (includes provisioning of nutrients for embryogenesis)
Carbon is for structural and energetic purposes
Phosphorus is for structural purpose only
Differences in assimilation efficiency
Differences in specific maintenance rate
Differences in overhead costs

7. P-rich food (=> Carbon limitation)
P-poor food
(=> Phosphorus limitation)

8. TER is size-dependent
TER = critical C:P ratio in the food at which individual switches from C- to P-limitation
Carbon-limitation
Phosphorus-limitation
P-rich food
P-poor food

9. (some) Population consequences
Population extinction with resource enrichment (dilution effect)
Alternative stable states: [low food density, high food quality] vs [high food density, low food quality]
Dampening / stabilization of population cycles

10. Biomass overcompensation
Total
Juveniles
Adults
Decrease in phosphorus concentration = decrease in adult performance (but not juveniles)
Decrease in population abundance
Carbon limitation
Phosphorus limitation
Increase in food density
(Much) increase in both juvenile performance
More transition of biomass to adult stages
Increase in adult biomass

11. Conclusions
Numerous potential implications of biomass overcompensation
Interactions between stoichiometric- and size- dependent effects
Can reverse the scaling of competition predicted by allometric scaling of ingestion and maintenance

12. (Personn and de Roos 2013)