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Ranking Species in Mutualistic Networks - Virginia Domínguez García and Miguel Á. Muñoz

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Ranking Species in Mutualistic Networks - Virginia Domínguez García and Miguel Á. Muñoz

  1. 1. Ranking Species in Mutualistic Networks Virginia Domínguez García and Miguel Á. Muñoz Lake Como Quantitative Laws II – June 2016 Statistical Physics and Complex Systems Group
  2. 2. Ranking Species in Mutualistic Networks – Mutualistic Interactions Mutualistic interactions Mutual beneficial interplay: Bee obtains nutrients in exchange for its pollination service
  3. 3. Mutualistic interactions Ranking Species in Mutualistic Networks – Mutualistic Interactions 90 % tropical trees Needs mutualism 70 % of crops needs bees Ubiquitous 90% of tropical trees are involved
  4. 4. Mutualistic interactions Ubiquitous 90% of tropical trees are involved Interactions can involve hundreds of species Tight coevolution: one to one specialization Mutualistic bipartite Networks Ranking Species in Mutualistic Networks – Mutualistic Interactions
  5. 5. Mutualistic interactions Bipartite: 2 Different set of nodes PlantsAnimals Mutualistic bipartite networks Ranking Species in Mutualistic Networks – Mutualistic Networks
  6. 6. Mutualistic interactions Bipartite: 2 Different set of nodes PlantsAnimals Interactions Ranking Species in Mutualistic Networks – Mutualistic Networks
  7. 7. Ranking Species in Mutualistic Networks – Mutualistic Networks specialistgeneralist specialist
  8. 8. Specialist (few partners) Specialist Specialist Generalist (many partners) specialistgeneralist Ranking Species in Mutualistic Networks – Mutualistic Networks specialist
  9. 9. Specialist (few partners) Specialist Specialist Generalist (many partners) specialistgeneralist Ranking Species in Mutualistic Networks – Mutualistic Networks specialist Measures number of shared neighbours =
  10. 10. Mutualistic Networks – External perturbation The International Union for Conservation of Nature has evaluated 52,205 species, depicted here, for their ability to survive
  11. 11. Mutualistic Networks – External perturbation How to identify the most important species in the network?
  12. 12. If we identify important species the network will collapse fast Ranking Species in Mutualistic Networks - Framework FRAMEWORK: DECONSTRUCTING ECOSYSTEMS We do not know how these networks are assembled Other strategy Tear them down Search for the most efficient way to destruction
  13. 13. PageRank A node is important if linked to important nodes Closeness Less distance to others Ranking Species in Mutualistic Networks - Framework FRAMEWORK: DECONSTRUCTING ECOSYSTEMS WHICH RANKING ? Degree More connections Betweenness Bottlenecks Nestedness Contribution to nestedness Eigenvector Overlap with leading eigenvalue of A
  14. 14. Ranking Species in Mutualistic Networks - Framework FRAMEWORK: MusRank Ranking algorithm for mutualistic networks Inspired in a recent work in econometrics Products
  15. 15. Ranking Species in Mutualistic Networks - Framework FRAMEWORK: MusRank Ranking algorithm for mutualistic networks Inspired in a recent work in econometrics Active species Passive species Importance Vulnerability Determined by number and vulnerability of partners (Linear) Bounded by the less important partner (Non-linear)
  16. 16. Ranking Species in Mutualistic Networks FRAMEWORK: MusRank Adjacency matrix ( ) ( ) ( ) ( ) Active Passive - Importance Vulnerability + - +
  17. 17. ( ) ( ) ( ) ( ) Ranking Species in Mutualistic Networks FRAMEWORK: MusRank FIX PONT Ranking of Importance of Active species Ranking of Vulnerability of Passive species Independent of initial conditions Active Passive - Importance Vulnerability + - +
  18. 18. ( ) ( ) ( ) ( ) Ranking Species in Mutualistic Networks FRAMEWORK: MusRank FIX PONT Ranking of Importance of Active species Ranking of Vulnerability of Passive species Independent of initial conditions
  19. 19. Ranking Species in Mutualistic Networks FRAMEWORK: Evaluating a ranking Extinction curve Active Passive Decreasingrank
  20. 20. Ranking Species in Mutualistic Networks FRAMEWORK: Evaluating a ranking Extinction Area Active Passive 0 1 1 destructive ranking 0 1 1 not destructive ranking OK! Decreasingrank Active Passive
  21. 21. Ranking Species in Mutualistic Networks RESULTS: MusRank PERFORMANCE Genetic Algorithm best RESULT: The ranking provided by MusRank outperforms all others RESULT: Reversing Active/Passive roles do not change results Robust algorithm Distance from each ranking to the genetic algorithm over all dataset (60 networks)
  22. 22. Ranking Species in Mutualistic Networks Take home message Mutualistic networks -mutual benefit interplay -hundred of species involved -characteristic features: Degree heterogeneity (Generalists and specialists), robust core, phylogeny groups, nestedness,… -Mutualistic interactions are very important for biodiversity manteinance. Rankig species -protocol to quantify “lethality” of a ranking -MusRank: best method to asses species importance in mutualistic networks WE ARE IMPORTANT !! Oh, No!!I’m more important than you are ! hehehe Thanks for Your attention !!

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