Biodiversity Hotspots and Endemism

How conservation priorities are set by concentrating effort on regions that combine exceptional endemic richness with severe threat.

Definition

Endemism is the occurrence of a taxon only within a defined geographic region. A biodiversity hotspot is a region that meets two criteria: it harbours a high number of endemic plant species and has lost a large fraction of its original primary vegetation, marking it as both irreplaceable and threatened.

Scope

Covers endemism — the restriction of species to particular geographic areas — and the hotspot approach to global conservation prioritization, including its defining criteria, the major hotspots, and alternative prioritization schemes such as wilderness areas and ecoregions. Examines the rationale, influence, and criticisms of hotspot-based targeting. Excludes general spatial gradients (sibling topic) and on-the-ground reserve management (treated under protected areas).

Core questions

• What makes a region qualify as a biodiversity hotspot?
• Why is endemism central to setting conservation priorities?
• How much of global biodiversity is concentrated in hotspots?
• What are the limitations of the hotspot approach?

Key concepts

• Endemism
• Biodiversity hotspot criteria
• Irreplaceability and vulnerability
• Centres of plant diversity
• Wilderness areas and ecoregions
• Range-restricted species

Key theories

Hotspot prioritization

Because endemic, threatened species are geographically concentrated, focusing conservation investment on a limited set of hotspots can protect a large share of global biodiversity at relatively low cost — an efficiency argument that reshaped global funding.

Irreplaceability and vulnerability

Conservation priority combines how unique a region's biota is (irreplaceability, driven by endemism) with how imminently it is threatened (vulnerability); hotspots score high on both axes.

Clinical relevance

The hotspot concept has been one of the most influential ideas in applied conservation, directing hundreds of millions of dollars of investment toward a small number of regions. Endemism mapping continues to guide protected-area placement, but reliance on hotspots alone risks neglecting species-poor yet ecologically important systems.

History

Myers introduced the hotspots idea for tropical forests in 1988 and expanded it in 1990. The 2000 Nature paper formalized quantitative criteria and identified 25 hotspots, catalysing the strategies of organizations such as Conservation International. Competing global schemes — endemic bird areas, the Global 200 ecoregions, and major tropical wilderness areas — emerged around the same period.

Debates

Are hotspots the right basis for global prioritization?

Critics argue that hotspots defined by plant endemism may not align with other taxa, neglect low-diversity but irreplaceable systems, and overlook intactness; defenders note their efficiency and demonstrated mobilizing power.

Key figures

• Norman Myers
• Russell A. Mittermeier
• Gustavo da Fonseca

Seminal works

• myers2000
• primack2014
• groom2006

Frequently asked questions

What is an endemic species?

A species found naturally only in one particular area and nowhere else. Islands and isolated mountains often have many endemics, which makes them both biologically distinctive and vulnerable, since losing the habitat means losing the species entirely.

How many biodiversity hotspots are there?

The original 2000 analysis identified 25 hotspots; the number has since been revised upward to around 36 as the framework has been refined. Together they cover a small fraction of land area but contain a large share of endemic plants and vertebrates.