Biodiversity & Classification

Organisms are classified systematically from domain and kingdom to species by shared traits. The three-domain system divides bacteria, archaea, and eukarya, and species names follow binomial nomenclature. Species diversity combines richness (number of species) with evenness (how individuals are shared), and we conserve genetic, species, and ecosystem levels. Slide evenness and see how the diversity index changes even with the same species count.

Why classify organisms?

💡 Like a library classification system

①Libraries need a classification system to find books

②Organisms too — millions of species need systematic organization

③Classified into groups (taxa) by shared characteristics

④DNA sequence comparison reveals exact classification relationships

⑤Why tropical rainforests have high diversity: stable environment + abundant energy + varied habitats

3-Domain System and Classification Hierarchy

Classification Hierarchy

8 levels of biological classification

Species Diversity — Richness and Evenness

Evenness (0=one dominant, 10=even)5

🔍 Try changing the evenness!

①Same 4 species but diversity differs by evenness

②One species dominates → diversity index (H') low

③All species even → diversity index (H') max

④Species diversity = richness (number) + evenness (distribution)

⑤Healthy ecosystems tend toward higher evenness

Three Levels of Biodiversity

Biodiversity

genetic diversity + species diversity + ecosystem diversity

all three levels must be conserved

💡 Meaning of three levels

①Genetic diversity: gene variation within a species (e.g., human blood types)

②Species diversity: number and even distribution of species in an ecosystem

③Ecosystem diversity: varied habitats — forests, wetlands, grasslands

④Loss at one level affects the others

⑤Why protecting endangered species matters: stability of the whole ecosystem

Summary

🎯 Exam Points

①3 Domains: Bacteria (no nucleus, peptidoglycan), Archaea (no nucleus, extreme env.), Eukarya (nucleus)

②8 levels: Domain-Kingdom-Phylum-Class-Order-Family-Genus-Species

③Binomial: Genus (capital) + species (lowercase), italics

④Species diversity = richness + evenness

⑤Biodiversity 3 levels: genetic, species, ecosystem

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