Taxonomy and Biodiversity
What this domain tests
Taxonomy and Biodiversity examines classification, binomial nomenclature, phylogenetic relationships, and the measurement of biodiversity. Questions may ask you to interpret a hierarchy, a cladogram, or sample data.
Core rules and concepts
- The taxonomic hierarchy runs domain, kingdom, phylum, class, order, family, genus, species. A scientific name is binomial: genus capitalized, species lowercase, usually italicized.
- Modern classification is phylogenetic: groups should reflect common ancestry. Molecular data often revise traditional morphology-based groupings.
- Species richness is the number of species present; evenness describes how similar abundances are. Two communities can have equal richness but different diversity because of evenness.
- Sampling must be representative. Quadrats estimate plant or sessile-organism abundance; transects detect zonation; mark–recapture estimates mobile populations.
Worked example
A sample contains four species with abundances 50, 30, 15, and 5 out of 100 individuals. Species richness = 4. Using Simpson’s index, D = 1 − Σp². Proportions are 0.50, 0.30, 0.15, and 0.05; Σp² = 0.25 + 0.09 + 0.0225 + 0.0025 = 0.365. So D = 1 − 0.365 = 0.635. Reasoning: D rises when individuals are spread more evenly among species.
Traps
Do not write species names with a capitalized species epithet. Do not treat “kingdom” as the most inclusive rank; domain is higher. Do not equate richness with diversity. In cladograms, branch order does not mean one extant species is “older” than another.