1. COMPETITION – COLONIZATION TRADE-OFF AND COEXISTENCE Ants and Acacia trees in Eastern Africa Angelica Cuevas Francesca Palmeira Irina Barros Mauricio Montellano Paulo Oliveira Raul Barriga

3. Acacia drepanolobium

5. Herbivory

6. Mutualism Acacia - Ants

7. Mutualism Acacia - Ants Shelter

8. Mutualism Acacia - Ants Shelter Food

9. Mutualism Acacia - Ants Shelter Food

10. THE SYSTEM Competition –Colonization trade-off

11. THE SYSTEM Competition –Colonization trade-off > Dispersion and Colonization >> Crematogaster sjostedtiC. mimosaeC. nigricepsTetraponera penzigi

12. THE SYSTEM Competition –Colonization trade-off > < Dispersion and Colonization Competition > < > < Crematogaster sjostedtiC. mimosaeC. nigricepsTetraponera penzigi

13. THE QUESTION How can the tree dynamics (growth, birth and death) affect the coexistence of the ants?

14. THE MODEL Competition –Colonization trade-off and Coexistence Strong Competitor Good Colonizer

15. THE MODEL Competition –Colonization trade-off and Coexistence Strong Competitor Good Colonizer Species 1

16. THE MODEL Competition –Colonization trade-off and Coexistence Strong Competitor Good Colonizer Species 2 Species 1

17. THE MODEL Competition –Colonization trade-off and Coexistence Young Mature

18. α > β μ m < μ y D < β α m > α y G e < G i THE MODEL Competition –Colonization trade-off and Coexistence Colonization rates Mortality rates Conquer and colonization rates Colonization rates for all ants Growth rates

19. dT ye /dt = rT m – G e T ye – α y T 1 T ye – β y T 2 T ye – μ y TT ye dT y1 /dt = α y T 1 T ye – G i T y1 – a y T 2 T y1 – μ y TT y1 dT y2 /dt = β y T 2 T ye + a y T 2 T y1 – G i T y2 – μ y TT y2 dT me /dt = G e T ye – α m T 1 T me – β m T 2 T me – μ m TT me dT m1 /dt = G i T y1 + α m T 1 T me – a m T 2 T m1 – μ m TT m1 dT m2 /dt = G i T y2 + β m T 2 T me + a m T 2 T m1 – μ m TT m2 THE MODEL Competition –Colonization trade-off and Coexistence Young empty trees Young – species1 Young – species 2 Mature empty trees Mature - species 1 Mature – species 2

20. RESULTS Competition and Coexistence There is coexistence! - Predominance of the strongest - Strongest win on the mature trees, and loose at the young one

21. RESULTS Evaluating change in Parameters - If the strongest species is fast enough, the Weakest disappears. - The growth of the trees is not essential to coexistence - Different death rates are important to the proportion of ants

22. RESULTS Evaluating change in Parameters - The Strongest must be, indeed, stronger then the Sp 1 in order to continue to exist.

23. THE MODEL 3 species Competition –Colonization trade-off and Coexistence Young Mature

24. RESULTS Competition and Coexistence There is also coexistence! - The middle species can survive alongside the others depending on the parameters.

25. RESULTS Evaluating change in Parameters At the start of the process, Sp1 increase. After the death of Sp2, Sp1 starts to decrease There is a “phase transition” on the number of coexisting ants species

26. RESULTS Evaluating change in Parameters

27. So this model predicts the existence of mature trees without ants. FIXED POINTS

28. CONCLUSIONS - Increase of Predominance of the strongest species depends of its rate of dispersion - Coexistence is possible because of the colonization-competition trade- off - The rate of growth and rate of birth affects the ratio between the species, but not necessarily the coexistence itself. - The coexistence depends of the rates of dispersion and colonization.

29. THANK YOU!

30. Questions?!