What Is Endemism?

Endemism describes the ecological state of a species being restricted to a particular location, such as an island, mountain range, or even a single lake. Endemic species are not naturally found outside their limited range, making them especially vulnerable to environmental changes and human activities. There are two main types of endemism:

• Paleoendemism: Ancient species that were once widespread but are now confined to a smaller area.

• Neoendemism: Recently evolved species that have not spread beyond their place of origin.

Where Is Endemism Most Common?

1. Islands: Natural Laboratories of Endemism

Islands are classic hotspots of endemism. Their geographic isolation acts as a barrier, preventing species from spreading to other regions. Over time, species on islands evolve independently, leading to the development of unique flora and fauna. For example:

• The Galapagos Islands are famous for their endemic finches.

• The Devil’s Hole pupfish is restricted to a single spring in Nevada, USA.

• The Socotra Archipelago harbors numerous plant and animal species found nowhere else13.

2. Mountain Ranges: Sky Islands of Biodiversity

Mountain ranges also foster high levels of endemism. The steep gradients in climate and habitat across different elevations create isolated environments, often referred to as “sky islands.” Species adapted to the cool, unique conditions at higher elevations are often unable to disperse to other areas, resulting in a concentration of endemic species. Notable examples include:

• The Western Ghats and Eastern Himalayas in India.

• The Sierra Nevada and Cascade ranges in North America.

• The Andes in South America2367.

Mountains are recognized as main centers of endemism due to increased speciation and reduced extinction rates, driven by their topographic complexity and environmental heterogeneity2.

Why Not Grasslands or Plateaus?

While grasslands and plateaus can support unique species, they generally lack the geographic isolation required for high levels of endemism. The absence of strong natural barriers allows for greater movement and gene flow between populations, reducing the likelihood of species evolving in isolation.

The Science Behind Endemism in Islands and Mountains

• Geographic Barriers: Oceans, steep slopes, and valleys isolate populations, limiting gene flow and promoting speciation.

• Specialized Adaptations: Endemic species often develop unique traits to survive in their specific habitats, making them highly specialized.

• Vulnerability: Because endemic species are restricted to small areas, they are particularly susceptible to extinction due to habitat loss, climate change, or invasive species.

Conservation Importance

Regions with high endemism are often prioritized for conservation because the loss of endemic species means global extinction. Protecting islands and mountain ranges is crucial for preserving the planet’s unique biological heritage.

Conclusion: The Correct Answer

Among the options given, islands are especially renowned for their high levels of endemism, followed closely by mountain ranges. Both environments provide the isolation necessary for unique species to evolve and persist123. Grasslands and plateaus, while important ecosystems, do not typically exhibit the same degree of endemism.

Correct answer:
(2) Island