Biodiversity & Habitat Fragmentation Lab
Explore species diversity indices, the species-area relationship, and the effects of habitat fragmentation on biodiversity. Collect survey data, run island biogeography experiments, and investigate how wildlife corridors mitigate species loss.
The island and fragmentation calculations use illustrative constants. The fragmentation model assumes overlapping species pools and 40% corridor recovery of modeled loss. It does not estimate a real habitat.
Guided ExperimentDiversity Indices from Species Survey Data
How do you expect Simpson and Shannon diversity indices to differ between a community with even species abundances versus one dominated by a single species?
Write your hypothesis in the Lab Report panel, then click Next.
These calculations are deterministic. The species-area constants are illustrative. Fragmentation assumes all fragments share the same species pool, and a corridor restores 40% of the modeled loss. Real communities can differ. Each recorded row identifies its experiment and keeps its original fields when the mode changes.
Controls
Results
Rank-Abundance Curve
Data Table
(0 rows)| # | Experiment | Individuals | Species counts | Simpson 1-D | Mainland species | Trial | Species Richness | Simpson D | Shannon H′ | Evenness | Area(km²) | Distance(km) | Predicted Species | Equilibrium Species | Fragments | Corridor | Intact Species | Fragmented Species | Loss % |
|---|
Reference Guide
Diversity Indices
Simpson's Dominance Index measures the probability that two randomly selected individuals belong to the same species.
Shannon-Wiener Index accounts for both richness and evenness. Higher values indicate greater diversity.
Pielou's Evenness ranges from 0 to 1, where 1 means all species are equally abundant.
Species-Area Relationship
One of ecology's most robust patterns. Larger areas support more species, following a power law.
Where S is species richness, A is area, c is a constant depending on the taxonomic group, and z typically ranges from 0.15 to 0.35 (often around 0.25 for oceanic islands).
On a log-log plot, this becomes a straight line with slope z.
Island Biogeography
MacArthur and Wilson's theory predicts that island species richness results from a balance between immigration and extinction.
Immigration rate decreases as the island fills with species, while extinction rate increases. The equilibrium is where these rates cross.
Near islands have higher immigration rates. Large islands have lower extinction rates. Together these predict that large, close islands hold the most species.
Habitat Fragmentation
Habitat fragmentation can change biodiversity through edge effects, population size and isolation. Its effects depend on the species and landscape. This lab assumes a decline at fixed total area rather than predicting it from field evidence.
Each fragment behaves like a small island, supporting fewer species than the original whole. Wildlife corridors can partially restore connectivity by allowing species to disperse between fragments.
Fragmentation is one of the leading causes of biodiversity loss worldwide, making corridor design a key conservation strategy.
