What is Biodiversity and How Do We Classify Organisms?
Biodiversity is the variety of all living things on Earth — from individual differences within a species to the vast array of ecosystems and habitats. Understanding biodiversity and how we classify and organize life is central to ecology, conservation and evolutionary biology.
Biodiversity has three levels: species diversity (number of different species), genetic diversity (variation within species), and ecosystem diversity (range of habitats and communities). Classification systems organize this diversity into hierarchical groups.
- •Number of different species in an area
- •Example: rainforest with 500 tree species vs. arctic tundra with 50
- •Measured as species richness
- •Genetic variation within a single species
- •Example: dog breeds (chihuahua vs. great dane) from same species
- •Ensures adaptability to change
Step-by-step worked examples
A forest has 12 tree species, 8 bird species, 15 insect species and 3 mammal species. What is the total species richness?
Species richness = total number of species = 12 + 8 + 15 + 3 = 38 species
Why is a forest with 40 similar tree species less diverse than one with 20 tree, 15 bird, 10 mammal and 10 insect species?
Species richness: both have 40 species, but the second has higher species evenness and ecosystem diversity. The first relies only on trees; the second has multiple functional groups → more stable ecosystem.
A population of wolves has only 5 breeding individuals. What biodiversity problem does this create?
Low genetic diversity — inbreeding increases, mutations accumulate, disease resistance drops. Small populations risk extinction from random events (bottleneck effect).
Flashcards
Quick quiz
Q1.Which is an example of genetic diversity?
Q2.An island has 20 bird species, a mainland has 80. Which has greater biodiversity?
Q3.Why does a small population of endangered animals lose genetic diversity?
Q4.Ecosystem diversity refers to…
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Common mistakes
Biodiversity means all species are equally common. — Correct: Biodiversity includes both richness (number of species) and evenness (how equally abundant they are).
A forest with 100 identical species is more diverse than one with 50 different species. — Correct: 50 different species = higher genetic and ecosystem diversity; 100 identical = low diversity, high extinction risk.
Genetic diversity and species diversity are the same thing. — Correct: Genetic diversity = variation within species; species diversity = number of different species.
Tropical rainforests have the most biodiversity because they're warm. — Correct: Rainforests have high biodiversity due to stable climate, complex structure and ancient evolution — not temperature alone.
FAQ
What is biodiversity?
The variety of all life on Earth across three levels: species (number of different species), genetic (variation within species) and ecosystem (habitat diversity).
Which region has the most biodiversity?
Tropical rainforests, coral reefs and wetlands host the highest biodiversity, despite covering only ~7% of Earth's surface.
Can biodiversity ever increase?
Yes — speciation (new species from existing ones) adds species diversity. But current extinction rates far exceed speciation.
How does biodiversity loss affect humans?
Loss of food sources, medicines, pollinators, water purification; reduced resilience to climate change and disease.