ranking species in mutualistic networks - virginia domínguez garcía and miguel Á. muñoz
TRANSCRIPT
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
Ranking Species in Mutualistic Networks – Mutualistic Interactions
Mutualistic interactions
Mutual beneficial interplay:
Bee obtains nutrients in exchange for its pollination
service
Mutualistic interactions
Ranking Species in Mutualistic Networks – Mutualistic Interactions
90 % tropical trees
Needs mutualism
70 % of cropsneeds bees
Ubiquitous 90% of tropical trees are involved
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
Mutualistic interactions
Bipartite: 2 Different set of nodes PlantsAnimals
Mutualistic bipartite networks
Ranking Species in Mutualistic Networks – Mutualistic Networks
Mutualistic interactions
Bipartite: 2 Different set of nodes PlantsAnimals
Interactions
Ranking Species in Mutualistic Networks – Mutualistic Networks
Ranking Species in Mutualistic Networks – Mutualistic Networks
specialistgeneralist
specialist
Specialist (few partners)
Specialist
Specialist Generalist(many partners)
specialistgeneralist
Ranking Species in Mutualistic Networks – Mutualistic Networks
specialist
Specialist (few partners)
Specialist
Specialist Generalist(many partners)
specialistgeneralist
Ranking Species in Mutualistic Networks – Mutualistic Networks
specialist
Measures number of shared
neighbours
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Mutualistic Networks – External perturbation
The International Union for Conservation of
Nature has evaluated 52,205 species, depicted
here, for their ability to survive
Mutualistic Networks – External perturbation
How to identify the most important species in the network?
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 strategyTear them down
Search for the most efficient way to destruction
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
Ranking Species in Mutualistic Networks - Framework
FRAMEWORK: MusRank Ranking algorithm for mutualistic networks
Inspired in a recent work in
econometrics Products
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)
Ranking Species in Mutualistic Networks
FRAMEWORK: MusRank
Adjacency matrix
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Act
ive
Passive
-Imp
ort
an
ce
Vulnerability
+
- +
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Ranking Species in Mutualistic Networks
FRAMEWORK: MusRank
FIXPONT
Ranking of
Importance of Active
species
Ranking of
Vulnerability of
Passive species
Independent of initial
conditions
Act
ive
Passive
-Imp
ort
an
ce
Vulnerability
+
- +
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Ranking Species in Mutualistic Networks
FRAMEWORK: MusRank
FIXPONT
Ranking of
Importance of Active
species
Ranking of
Vulnerability of
Passive species
Independent of initial
conditions
Ranking Species in Mutualistic Networks
FRAMEWORK: Evaluating a ranking
Extinction
curve
Active PassiveD
ecr
ea
sin
gra
nk
Ranking Species in Mutualistic Networks
FRAMEWORK: Evaluating a ranking
Extinction
Area
Active Passive
0 1
1destructive ranking
0 1
1not destructive ranking
OK!
De
cre
asi
ng
ran
kActive Passive
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)
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 AREIMPORTANT !!
Oh, No!!I’m more importantthan you are ! hehehe
Thanks for Your
attention !!