# Ecology: Multispecies Competition A stochastic community model. **Several species compete for shared resources while immigration trickles in new individuals**, and the run shows how competition overlap and immigration rate together set richness, total abundance, and dominance. ## What it simulates - Tau-leaping approximation of Gillespie dynamics. - Per-species birth propensity from current abundance plus a flat immigration rate. - Death propensity that grows with crowding, mixing intraspecific and interspecific terms via a single overlap parameter. - Default run: six species, carrying capacity 100, modest competition overlap and immigration.  ## Run it on the Hub 1. Open the [Leibovich2022 Multispecies Competition Lab](https://hub.biosimulant.com/labs/1348127f-35df-4b01-9cdd-e75307c31063) on the public Hub. 2. Click **Run**. The default scenario runs for 500 time units. ## Inputs you can tune | Input | Meaning | |---|---| | `carrying_capacity` | Habitat carrying capacity. | | `birth_rate` | Per-capita birth rate. | | `death_rate` | Per-capita baseline death rate. | | `competition_overlap` | 0 = pure intraspecific competition; 1 = full interspecific competition. | | `immigration_rate` | Constant per-species immigration rate. | | `initial_abundance` | Starting abundance per species. | | `rng_seed` | Random seed for reproducibility. | ## What results to expect - **Per-species abundance**: stochastic fluctuations around a shared carrying capacity. Species can collapse to zero and re-enter through immigration. - **Community metrics**: total abundance, species richness, and Shannon diversity over time. - **Summary table**: final and extremal abundances, peak richness, and the dominant species at the end.  ## Reference Faithful Python port of the upstream Julia/Python Gillespie code from Leibovich et al. (2022), [BioModels MODEL2212080001](https://www.ebi.ac.uk/biomodels/MODEL2212080001). **Info:** Source on GitHub: [models-ecology — leibovich2022-multispecies-competition](https://github.com/Biosimulant/models-ecology/tree/main/labs/ecology-leibovich2022-multispecies-competition).