Time00:00

SeasonSpring

Plants–

Herbivores–

Predators–

Plants Herbivore (colour = camouflage gene) Predator Water Rock Infected Drag to paint / scatter.

Ecosystem & Evolution Lab

Plants, herbivores and predators live, eat, breed and die. Genes mutate; the environment decides who survives.

Time speed 1×

Seed

Environment & genetics

Plant growth 1.0× Mutation rate 8% Predator efficiency 1.0× Carrying capacity (herbivores) 1400 Season length 90 s

Immigration if extinct

Choose the Inspect tool and click an animal to see its genes, energy, age and ancestry.

Each line is scaled to its own maximum. Look for predators lagging behind prey – the Lotka–Volterra cycle.

A loop means cycles; a spiral inwards means a stable balance; a line to an axis means extinction.

Gene

HerbivoresPredators

Shannon index H′ = −Σ pᵢ ln pᵢ over animal colour morphs (6 herbivore + 6 predator bins). Higher means a more varied gene pool.

Natural selection & Lotka–Volterra

Natural selection needs three things: variation (mutation each birth), heredity (children copy parent genes) and differential survival (some genes leave more offspring). Nothing is designed – fast, well-camouflaged, efficient animals just breed more.
Trade-offs keep it interesting. Speed and vision burn energy, size stores more energy and is harder to catch but costs upkeep, a low reproduction threshold breeds early but with weaker young.
Camouflage: a prey colour close to the fertility of the ground it stands on reduces the range at which predators spot it. Rich and poor biomes favour different colours.
Lotka–Volterra: prey grow exponentially when predators are few (dx/dt = αx − βxy); predators grow by eating prey and starve without them (dy/dt = δxy − γy). The result is lagged boom-and-bust cycles, which appear as loops in the phase portrait.
Arms race: faster prey select for faster predators and vice versa – the Red Queen effect. Try the Arms race preset and watch the speed and vision lines climb together.
Disturbances (meteor, fire, drought, disease) crash populations; survivors repopulate and the gene pool can shift (a bottleneck).
A simplified model: asexual reproduction, one gene per trait, illustrative numbers.