Do multispecies communities need deep coevolutionary history to generate stabilizing interactions that maintain species coexistence? We investigate through computational analysis of Lotka-Volterra communities across a coevolutionary gradient.
Three complementary computational analyses addressing the open problem
Sweep θ from 0 (random assembly) to 1 (coevolved community) across Lotka-Volterra communities with S=10 species, 30 replicates per θ value, measuring NFD via invasion-from-rarity analysis.
Starting from θ=0, allow interaction coefficients to evolve via mutation and selection over 500 generations, testing whether NFD can emerge de novo through niche differentiation.
Decompose coexistence into stabilizing niche differences (1-ρ) and fitness ratios under Modern Coexistence Theory across the coevolutionary gradient (S=8, 50 replicates).
How does shared evolutionary history (θ) affect NFD strength and species persistence?
Can novel assemblages develop NFD through rapid evolution?
Stabilizing niche differences and pairwise coexistence across θ
Key metrics at selected θ values from the gradient sweep (S=10, 30 replicates)
| θ | Mean NFD | SD NFD | Surviving (of 10) | % Positive Invasion | 1-ρ (MCT) | Coexisting Pairs |
|---|---|---|---|---|---|---|
| 0.00 | +0.0728 | 0.0318 | 6.67 | 65.7% | 0.525 | 97.0% |
| 0.10 | +0.0896 | 0.0179 | 7.50 | 74.3% | 0.518 | 97.2% |
| 0.25 | +0.0742 | 0.0279 | 7.37 | 73.7% | 0.525 | 98.3% |
| 0.50 | +0.0628 | 0.0178 | 7.27 | 71.3% | 0.528 | 98.2% |
| 0.75 | +0.0426 | 0.0111 | 6.67 | 65.0% | 0.535 | 93.9% |
| 1.00 | +0.0027 | 0.0023 | 4.00 | 40.0% | 0.545 | 85.6% |
Metrics at start and end of 500-generation simulation (S=10, θinitial=0)
| Metric | Generation 0 | Generation 499 | Change |
|---|---|---|---|
| Mean NFD | +0.0859 | +0.0866 | +0.8% |
| Mean αij | 0.618 | 0.569 | -8.0% |
| Surviving species | 9 | 10 | +1 |
| Fraction positive invasion | 0.90 | 0.80 | -0.10 |
Novel assemblages (θ=0) exhibit positive NFD with mean invasion growth rate +0.0728 and 65.7% of species achieving positive invasion rates. Stabilizing niche differences (1-ρ=0.525) are nearly as large as in coevolved communities.
Increasing θ reduces mean NFD and fraction of coexisting pairs because structured niche partitioning introduces fitness asymmetries between neighboring species on the niche axis.
Novel assemblages maintain positive NFD over 500 generations while mean interspecific competition decreases by 8.0% through evolved niche differentiation, suggesting rapid coevolution can stabilize novel communities.