Table 1 Different classes of PDE associated with the discrete model in appropriate parameter regimes.

From: Co-operation, Competition and Crowding: A Discrete Framework Linking Allee Kinetics, Nonlinear Diffusion, Shocks and Sharp-Fronted Travelling Waves

 

Nonlinear diffusivity

Degenerate diffusivity

Number of non-degenerate zeroes

Negative diffusivity

Source Term

Grouped agent death

Relevant previous analysis

Case 1

x

x

0

x

Fisher

x

18, 19, 20, 21,24,25,27,29

Case 2: Sub-case 1

✓

x

0

x

Fisher

x

58, 59, 60

Case 2: Sub-case 2

✓

✓

0

x

Fisher

x

40,57,69,70

Case 2: Sub-case 3

✓

x

2

✓

Fisher

x

36

Case 2: Sub-case 4

✓

✓

1

✓

Fisher

x

38

Case 3

x

x

0

x

Fisher

✓

18, 19, 20, 21,24,25,27

Case 4: Sub-case 1

✓

x

0

x

Fisher

✓

58, 59, 60

Case 4: Sub-case 2

✓

✓

0

x

Fisher

✓

40,57,69,70

Case 4: Sub-case 3

✓

x

2

✓

Fisher

✓

36

Case 4: Sub-case 4

✓

✓

1

✓

Fisher

✓

38

Case 4: Sub-case 5

✓

x

1

✓

Fisher

✓

38

Case 5

x

x

0

x

Allee

x

15,19,22,23,25,26,28,30

Case 6: Sub-case 1

✓

x

0

x

Allee

x

69,71

Case 6: Sub-case 2

✓

✓

0

x

Allee

x

41,72

Case 6: Sub-case 3

✓

x

2

✓

Allee

x

37

Case 6: Sub-case 4

✓

✓

1

✓

Allee

x

39

Case 7

x

x

0

x

Allee

✓

15,19,22,23,25,26,28,30

Case 8: Sub-case 1

✓

x

0

x

Allee

✓

69,71

Case 8: Sub-case 2

✓

✓

0

x

Allee

✓

41,72

Case 8: Sub-case 3

✓

x

2

✓

Allee

✓

37

Case 8: Sub-case 4

✓

✓

1

✓

Allee

✓

39

Case 8: Sub-case 5

✓

x

1

✓

Allee

✓

39

  1. An Allee source term can correspond to either the weak, strong or reverse Allee effect. Degenerate diffusivity refers to the case where F(C*) = R(C*) = 0 for some value C*. A detailed analysis of all cases is presented in the Supplementary Material.