Endemism

What endemism measures

A species is endemic to a region if its entire global range falls within that region. A species found only on Madagascar is Madagascar-endemic. A species found in only one valley of the [[albertine-rift|Albertine Rift]] is locally endemic. A species found across the entire Holarctic — like the gray wolf — is not endemic anywhere; it is cosmopolitan.

Endemism rate is the proportion of a region’s species that are endemic to it. High endemism rates are produced by some combination of three factors:

• Geographic isolation. Islands, mountain ranges that act as evolutionary islands, and continental fragments separated for long periods all develop high endemism because populations evolve in isolation without genetic mixing with continental relatives. Madagascar (separated from Africa ~165 million years ago, from India ~88 million years ago) has had time to evolve a flora and fauna almost entirely distinct from any other landmass.
• Habitat heterogeneity. Regions with steep environmental gradients (elevation, rainfall, soil types) often support many narrowly-adapted species each occupying a distinct micro-niche. The [[western-ghats|Western Ghats]] combine elevation gradient, rain-shadow effect, and tropical location to produce extraordinary endemism.
• Climatic refugia. Regions that retained habitable conditions during glacial periods (when global temperate-zone climates shifted dramatically) sometimes preserved relict populations and provided long-term continuous evolutionary substrate.

The endemism hotspots

The “biodiversity hotspot” framework (Norman Myers, 1988; refined in Myers et al. Nature 2000) identifies 36 global regions combining extreme endemism (≥1,500 endemic plant species) with extreme habitat loss (≤30% of original vegetation remaining). These hotspots together cover ~2.5% of global terrestrial surface but contain ~50% of all vascular plant endemic species and ~43% of all terrestrial vertebrate endemic species.

Notable hotspots discussed elsewhere in the wiki:

• [[cape-floristic-region|Cape Floristic Region]] — 9,000 plant species in 90,000 km², 70% endemic. The most species-dense temperate flora on Earth.
• [[mediterranean-basin|Mediterranean Basin]] — 25,000 plant species, ~half endemic.
• [[western-ghats|Western Ghats]] — 7,400 plant species, 1,800 endemic; ~60% of amphibians endemic.
• [[atlantic-forest|Atlantic Forest]] — 20,000 plant species, ~half endemic.
• Cerrado — 12,000 plant species, 44% endemic.
• Madagascar — ~12,000 plant species, 80% endemic; entirely distinct mammal, reptile, and amphibian faunas.
• New Zealand — ~80% plant endemism, ~90% insect endemism.
• Tropical Andes — perhaps the most species-rich hotspot of all, with 30,000+ plant species and high endemism rates.

Why endemism matters

Endemic species cannot be replaced from elsewhere. If a species’ entire global range is in one place and that place is destroyed, the species is extinct. Conservation biology therefore weights endemic-rich regions disproportionately — losing 1% of habitat in a region with 50% endemism is much more consequential globally than losing 1% in a region with 1% endemism, because the cosmopolitan species can persist elsewhere while the endemics cannot.

The flip side: endemic species are often locally significant culturally, medicinally, and agriculturally. The medicinal-plant traditions of the [[soliga|Soliga]], [[toda|Toda]], and other Western Ghats Indigenous peoples; the fynbos knowledge of Cape Floristic peoples; the agricultural diversity of the high Andean altiplano — all are systems of knowledge built on locally-endemic biota that exists nowhere else. Endemism conservation and Indigenous knowledge sovereignty are therefore typically aligned even when conservation institutions and Indigenous communities have not historically recognized this.

See also

Auto-generated from this entry’s typed relations: frontmatter, grouped by relation type so the editorial signal isn’t flattened.

• Demonstrated by: [[cape-floristic-region]] · [[western-ghats]] · [[atlantic-forest]] · [[albertine-rift]]

Sources

• Myers et al., “Biodiversity hotspots for conservation priorities” (Nature 2000)
• Conservation International — Hotspots
• Wikipedia — Endemism, Biodiversity hotspot

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A concept entry in the 0mn1.one wiki.