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FormulatingEvolutionaryDynamicsofOrganism-
EnvironmentCouplingsUsingGraphProductMultilayer
Networks Hiroki Sayama andYaneer Bar-Yam
sayama@binghamton.edu
Evolution
2
息 McDougal Littell Inc.
3
Reproduction
with variation
(crossover, mutation)
Selection
with competition
Parallel search
over possibility space by
accumulating
incremental changes
Offspring
Offspring
Offspring
Offspring
Offspring
Offspring
Offspring
Offspring
Offspring
Offspring
Parent
Parent
Parent
Parent
Parent
4
5
f
Reproduction
with variation
(crossover, mutation)
Selection
with competition
Offspring
Offspring
Offspring
Offspring
Offspring
Offspring
Offspring
Offspring
Offspring
Offspring
Parent
Parent
Parent
Parent
Parent
6
Reproduction
with variation
(crossover, mutation)
Selection
with competition
Offspring
pool
Parent
pool
Mean-field
assumption is adopted
for both selection and
reproduction
7
息 nationalgeographic.com
8
9
PRE 65, 051919 (2002)
PRL 88, 228101 (2002)
Cons. Biol. 17, 893-900 (2003)
Here we present a theoretical framework
that formulates the evolution of general
organism-environment couplings using
graph product multilayer networks.
 Review of graph product multilayer networks
 Organism-environment coupling space
 Reaction-diffusion evolutionary dynamics
 Numerical study
10
Review of Graph
Product Multilayer
Networks
11
Sayama (2017) J. Complex Netw., cnx042
https://doi.org/10.1093/comnet/cnx042
https://arxiv.org/abs/1701.01110
12
2x2 = 4
13
x = ?
14
1
2 3
4
a
b
c
{1, 2, 3, 4} {a, b, c}x
(1, a)
(1, b)
(1, c)(3, a)
(3, b)
(3, c)
(2, a)
(2, b)
(2, c) (4, a)
(4, b)
(4, c)Meta nodes
DegreeSpectra: ExactSolutions
15
(1, a)
(1, b)
(1, c)(3, a)
(3, b)
(3, c)
(2, a)
(2, b)
(2, c) (4, a)
(4, b)
(4, c)
(1, a)
(1, b)
(1, c)(3, a)
(3, b)
(3, c)
(2, a)
(2, b)
(2, c) (4, a)
(4, b)
(4, c)
(1, a)
(1, b)
(1, c)(3, a)
(3, b)
(3, c)
(2, a)
(2, b)
(2, c) (4, a)
(4, b)
(4, c)
Layers
Layers
Graph Product
Multilayer Networks
Cartesian product
Direct product
Strong product
16
Cartesian
product
17
18
1
2 3
4
a
b
c
{1, 2, 3, 4} {a, b, c}x
(1, a)
(1, b)
(1, c)(3, a)
(3, b)
(3, c)
(2, a)
(2, b)
(2, c) (4, a)
(4, b)
(4, c)
19
, : Kronecker sum and product
DegreeSpectra: ExactSolutions
20
lH
1 lH
2  lH
n
lG
1
lG
2

lG
m
lH
1 lH
2  lH
n
lG
1 lG
1+lH
1 lG
1+lH
2  lG
1+lH
n
lG
2 lG
2+lH
1 lG
2+lH
2  lG
2+lH
n
    
lG
m lG
m+lH
1 lG
m+lH
2  lG
m+lH
n
Direct
product
21
22
: Kronecker product
23
1
2 3
4
a
b
c
{1, 2, 3, 4} {a, b, c}x
(1, a)
(1, b)
(1, c)(3, a)
(3, b)
(3, c)
(2, a)
(2, b)
(2, c) (4, a)
(4, b)
(4, c)
DegreeSpectra: ExactSolutions
24
Sayama, H. (2016) DiscreteApplied Mathematics 205, 160-170.
https://doi.org/10.1016/j.dam.2015.12.006
lH
1 lH
2  lH
n
lG
1
lG
2

lG
m
lH
1 lH
2  lH
n
lG
1 lG
1lH
1 lG
1lH
2  lG
1lH
n
lG
2 lG
2lH
1 lG
2lH
2  lG
2lH
n
    
lG
m lG
mlH
1 lG
mlH
2  lG
mlH
n
Approximated Laplacian spectrum
Strong
product
25
26
, : Kronecker sum and product
27
1
2 3
4
a
b
c
{1, 2, 3, 4} {a, b, c}x
(1, a)
(1, b)
(1, c)(3, a)
(3, b)
(3, c)
(2, a)
(2, b)
(2, c) (4, a)
(4, b)
(4, c)
DegreeSpectra: ExactSolutions
28
Sayama, H. (2016) DiscreteApplied Mathematics 205, 160-170.
https://doi.org/10.1016/j.dam.2015.12.006
Approximated Laplacian spectrum
Organism-
Environment
Coupling Space
29
env-nodes
30
G
org-nodes
31
H
隆: spatial diffusion rate
(average link weight in G)
32
袖: type diffusion rate
(average link weight in H)
33
org-env combos GH
3434
Spatial & type diffusions as one diffusion process
Laplacian of GH very easy to obtain & analyze
Reaction-Diffusion
Evolutionary
Dynamics
35
36
Local population
dynamics
Diffusion on
GH
37
Local population
dynamics Environment-
independent
fitnesses
Environment-
dependent
fitnesses
隆: spatial diffusion rate
38
袖: type diffusion rate
How does 隆 affect the
fitnesses of organisms?
Numerical Study
39
40
G, 隆
H, 袖, FH
留, Fe
Dominant
eigenvector
of (F  L)
41
Dominant
eigenvector
of (F  L)
留, Fe
H, 袖, FH
G, 隆
Fixed
parameters
Random
weighted
graph with
20 nodes
Random
weighted
graph with
20 nodes
10-5 Random
weighted
diagonal
matrix
(20x20)
0.5
Random
weighted
diagonal
matrix
(400x400)
42
Dominant
eigenvector
of (F  L)
留, Fe
H, 袖, FH
G, 隆
Varied
parameter
10-5 ~ 102
43
n = 20,000
Actual fitness ~ inherent fitness
(non-spatial;
environment-independent)
Actual fitness 
inherent fitness
(spatial;
environment-
dependent)
44
留 = 0.0 留 = 0.1 留 = 0.2
留 = 0.4 留 = 0.5 留 = 0.6
留 = 0.8 留 = 0.9 留 = 1.0
45
袖 = 10-4 袖 = 10-3 袖 = 10-2
Conclusions
46
47
Multilayer networks can be
useful to study evolution.
48
Limitations
 Considered simple linear dynamics only
 No inter-species interactions considered
 Diffusion rates independent of organisms
 No analytical explanation (yet)
49
Next Steps
 Including nonlinear, coupled population
dynamics (e.g., replicator equations)
 Obtaining analytical conditions by
exploiting GPMNs spectral properties
50
DegreeSpectra: ExactSolutions
51
ThankYou
@hirokisayama

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Formulating Evolutionary Dynamics of Organism-Environment Couplings Using Graph Product Multilayer Networks