Species Interaction Dynamics

Interaction Type

B→A: 0 A→B: 0

Parameters

Interaction strength 0.60

Simulation speed 1.0×

Live Readouts

Population A 🟢

20.0

Population B 🟠

15.0

Elapsed generations

0.0

How it works

Both populations follow the generalized Lotka–Volterra two-species model, the standard ecological framework for classifying every pairwise species interaction by the sign of two coupling terms:

dA/dt = A·(rA − sA·A + iAB·B)
dB/dt = B·(rB − sB·B + iBA·A)

Here rA, rB are intrinsic growth rates, sA, sB are self-limitation from crowding/resources (each population's own carrying capacity), and iAB, iBA are the per-capita effect of one species' density on the other's growth rate. Every classical interaction type is just a choice of signs for (iAB, iBA):

Type	B → A	A → B
Mutualism	+	+
Competition	−	−
Predation	−	+
Parasitism	− (weak)	+ (weak)
Commensalism	0	+
Amensalism	−	0
Neutralism	0	0

Interaction strength — scales |iAB| and |iBA|; higher values push the pair further from independent logistic growth.
Predation vs. parasitism — same sign pattern, but a parasite's drain on the host and its own benefit are both kept small, since parasites rarely kill outright the way predators do.
The equations are integrated with a semi-implicit Euler step (10 substeps/frame, dt clamped) so the visible population curve stays numerically stable even near the mutualism instability threshold sA·sB < iAB·iBA.
Each visible sphere in the 3D scene represents roughly one unit of population; the swarm sizes grow and shrink live as the populations evolve.

Species A Species B

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