Environmental Science
Why Biodiversity Hotspots Coincide with Topographically Diverse Regions
Quick fact
More than 80% of the world's terrestrial biodiversity hotspots are located in mountainous regions, despite mountains covering only about 25% of Earth's land surface.
Why this is interesting
You've likely seen lush, species-rich valleys nestled between towering peaks, but why do so many of Earth's biodiversity hotspots sit in rugged, mountainous terrain? The answer lies in how topography crafts a cradle for life.
Read the full explanation
Understanding Why Biodiversity Hotspots Coincide with Topographically Diverse Regions
Think of a mountain range as a stack of different climate zones stacked vertically. As you climb from base to summit, temperature drops, rainfall changes, and sunlight differs. This creates a mosaic of habitats—from dense forests to alpine meadows—within a small area. Each distinct habitat can support its own set of species. Moreover, valleys and ridges act as barriers, isolating populations on different mountains. Over time, this isolation prevents gene flow, encouraging populations to evolve independently and become new species—a process known as allopatric speciation. So, topographic diversity not only hosts more habitats but also actively generates new species.
A deeper explanation
The coincidence of biodiversity hotspots with topographically diverse regions arises from a combination of ecological and evolutionary mechanisms. First, topographic complexity creates a wide array of microclimates and environmental gradients, offering a greater number of potential niches. This supports higher species diversity per unit area. Second, the physical barriers of valleys and ridges split populations into smaller, isolated groups. With limited gene exchange, these groups experience different selective pressures and can diverge genetically, eventually forming new species—especially in taxa with low dispersal abilities. Third, during periods of climate change (e.g., ice ages), mountains provide refugia: areas with stable microclimates where species can retreat and survive while surrounding lowlands become inhospitable. This allows ancient lineages to persist, preserving both evolutionary history and endemism. Together, these processes explain why regions like the Andes, the Himalayas, and the East African Rift are cradles of biodiversity and conservation priorities.