Among major terrestrial biomes, which has the greatest species diversity?

• A. Tropical Rainforest
• B. Desert
• C. Grassland
• D. Aquatic

Answer: (A)

The key idea here is that energy input and habitat structure drive how many species can coexist. Tropical rainforests receive a lot of sunlight and heavy, year-round rainfall, which fuels extremely high primary productivity. That enormous energy supports a vast diversity of plant life, creating a dense, layered habitat with emergent trees, a closed canopy, an abundant understory, and a vibrant forest floor. Each vertical layer offers distinct niches, resources, and microhabitats, so many different animals, insects, fungi, and microbes can specialize and occupy different parts of the ecosystem without directly outcompeting one another. The climate in the tropics is also relatively stable year-round, reducing extinction risks and allowing lineages to diversify over long timescales. In contrast, deserts have limited water and productivity, grasslands have fewer distinct habitats, and aquatic environments, while diverse, are not terrestrial. All of this points to tropical rainforests having the greatest species diversity among major terrestrial biomes.