Food Web Assembly - Niche Model & Extinction Cascades

Web Generation Model

Assembly Model

Network Parameters

Number of Species (S)

Connectance (C)

0.15

Basal Species Fraction

0.20

Dynamics

Extinction Threshold

0.50

Removal Strategy

Perturbations

Top Pred:

Consumers:

Basal:

Basal

Consumer

Top Pred

Extinct

Food Web Network

Trophic Pyramid

Degree Distribution

Robustness Curve (R50)

Species (S)

Links (L)

Connectance (C)

Link Density (L/S)

Mean Trophic Level

Max Chain Length

Secondary Extinctions

R50 Robustness

Food Web Assembly Models (Williams & Martinez 2000)

Niche Model: Each species has a niche value n ∈ [0,1] and eats species with niche values in a contiguous range below it. Cascade Model: Species only eat species with lower niche values (hierarchical). Connectance C = L/S² predicts network robustness. Higher connectance generally increases stability but R50 depends on network type and extinction thresholds.