This presentation is the result of a one-week student group work during the Southerm-Summer School on Mathematical-Biology, held in São Paulo, BR, in January 2012, http://www.ictp-saifr.org/mathbio

1. Indirect effects affects ecosystem
dynamics
The effect of non­lethal effects in planktonic
community
Alessandra Lütz; Garcia Guillerme, Maikol
Rodriguez, Thiago Couto, Caio Graciani,
Angel Segura

2. Biodiversity

3. You are
here
David M. Hillis, Derrick Zwickl, and Robin Gutell,
University of Texas.

4. Energy flow
Ecosystem functioning
Energy fluxes
Trophic models

5. Energy flow
Being eaten (predation)
Change in prey abundance
and traits
Modify community dynamics

6. Non Consumable Effects (NCE)
Trait­mediated indirect effects (TMI)
Do not imply biomass removal
Trait variation: Phenotipic (size),
behaviour (diel migration), etc

7. NCE effects
Inducible defenses
TMI

8. Non Consumable Effects (NCE)
Trait­mediated indirect effects (TMI)
Not new (Science 1971)

9. How relevant are NCEs to
community dynamics?

10. NCE are relevant for predator
­prey dynamics
Small experimental systems
Relevant (Significative change)
Planktonic

11. Plankton dynamics
Microbial primary producers
Cells or colonies
Hundreds of species
Carbon sinking
Fast generation time (days)
Easy to handle
Large size range

13. Plankton dynamics
Toxic blooms
Ecosystems integrity
Biodiversity loss
Human

14. NCE in plankton
Widely recognized

15. Seldomly taken into account
Few models include explicitly it effects
Long term dynamics of this effect
unexplored

16. Are NCE effects important for
community dynamics?

17. Hipothesis:
Inducible defenses modify community
dynamics because of changes in biomass
fluxes mediated by NCE
Objective
Analyse community dynamics when species
shown inducible defenses behaviour

18. Planktonic systems
Lots of information on basic
physiology
Morphology based functional groups
Nutrient (P limited)
Group I Group VII

19. Planktonic systems
Lots of information on basic
physiology
Morphology based functional groups
Nutrient (P limited)
Group I Group VII
Kruk et al., 2010

20. How to ensamble the “system”?
Predator­ “Daphnia”
Limiting resource­ Phosporus
Competing species

21. How to ensamble the “system”?
Predator­ “Daphnia”
Limiting resource­ Phosporus
Competing species
Explicit competition Group I Group
VII
P

22. How to ensamble the “system”?
Predator­ “Daphnia”
Limiting resource­ Phosporus
Competing species
Explicit competition Group I Group
VII
P

23. What if NCE?
Change for I to VII in the
prescence of Daphnia
Group I Group
VII
P

24. Lets put some maths!
Change for I to VII in the
prescence of Daphnia (m)
Group I Group
m VII
P

25. How does system behaves?
Change for I to VII in the
prescence of Daphnia (m)
Group I Group
m VII
P

26. Changes in the fixed points
M=0 (Exclusion) m=0.4 (Coexistence) Grou Grou
C or G­>0 C,G,Z,P > 0 pI m p VII
P

27. Sustained oscilations
Implications for biodiversity Grou
pI m
Grou
p VII
m=0 (Exclusion G) m=0.4 (Coexistence)
P

28. What about nature?
Coexistence­peaks Grou
pI m
Grou
p VII
Grou
p VII P
Grou
pI

29. Grou m Grou
NCEs are important
pI p VII
Non trivial effect (Peacor et al 2012) P
Influence dominance and coexistence
Explored in a mechanistic models based on
physiological principles (first time)

30. NCEs are important Grou
pI
m Grou
p VII
No data to compare with model output
P
Design of experiments for model evaluation
and biological parameters
Mathemathical tools (topological aspects)

31. Group I m Group VII
P

33. m>0
Grou m Grou
p VII
pI
P

34. m=0
Grou m Grou
p VII
pI
P

35. Grou
pI
m Grou
p VII
Similar behaviour
P
Similar patterns in simple and complex model
Similar model beahviour (needs more formal
analysis)
Other competing groups? More predators?