Island Biogeography

In the AI Story

The theory was developed in the context of Caribbean herpetology — lizards on islands. Wilson and MacArthur predicted that larger islands would support more species (because extinction rates would be lower on larger habitats) and that islands closer to the mainland would support more species (because immigration rates would be higher). Both predictions were confirmed across hundreds of islands and thousands of species. The theory became foundational to conservation biology, shaping the design of nature reserves, the management of fragmented habitats, and the understanding of why species diversity is not evenly distributed across the planet.

The extension to software markets is what this volume argues. The SaaS ecosystem before AI operated at a stable equilibrium: moderate immigration rate (building new software required capital and expertise) and low extinction rate (established companies were protected by network effects and switching costs). The equilibrium supported hundreds of companies, each occupying a niche, each protected by the friction of its category.

AI shifted both rates simultaneously. The immigration rate skyrocketed — building new software approached zero cost, and anyone with an idea could produce a working prototype in hours. The extinction rate also rose dramatically — the moats that protected established companies dissolved as their code became replicable in days. The double shift produced exactly the kind of rebalancing the theory predicts: rapid, chaotic redistribution toward a new equilibrium with fewer, larger, more resilient survivors occupying fundamentally different niches than the ones that preceded them.

The predictive power is not coincidental. It is structural. The Darwin-Schumpeter homology means that biological and economic ecosystems share governing dynamics, and a theory that correctly describes equilibrium and disruption in one substrate often transfers to the other with minimal modification. Wilson would not have been surprised that his Caribbean lizards predicted the SaaSpocalypse. He spent his career arguing that this kind of cross-substrate transfer is exactly what consilience looks like when it works.

Origin

Robert MacArthur and E.O. Wilson, The Theory of Island Biogeography (Princeton, 1967), emerged from MacArthur's mathematical ecology and Wilson's Caribbean fieldwork. The book transformed ecology from a largely descriptive discipline into a theoretical one with predictive mathematical models, and it remains one of the most-cited works in twentieth-century biology.

Key Ideas

Equilibrium is a rate balance. The number of species on an island is not a fixed carrying capacity but a dynamic equilibrium between ongoing immigration and extinction.

Size and distance govern rates. Larger habitats have lower extinction rates; closer habitats have higher immigration rates. Both predictions transfer to market ecosystems.

Rate shifts produce rebalancing. When either rate changes substantially, the equilibrium shifts rapidly. The shift is not linear — it is a new equilibrium with different composition, not merely fewer of the original occupants.

The surviving species share features. Rebalancing does not eliminate randomly. It selects for specific adaptive traits — in biology, deep ecological integration; in software, ecosystem value above the code layer.