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Difficulty: HardTaxonomy and Classification

A field biologist records the taxonomic classifications of four newly cataloged animal specimens:

• Specimen W and Specimen X share the same class, but belong to different orders.
• Specimen X and Specimen Y share the same genus, but represent different species.
• Specimen Y and Specimen Z share the same family, but belong to different genera.

Based on the Linnaean taxonomic hierarchy, which pair of specimens shares the greatest number of taxonomic categories and is therefore most closely related?

  1. A
    Specimen W and Specimen X
  2. Specimen X and Specimen YAnswer
  3. C
    Specimen Y and Specimen Z
  4. D
    Specimen W and Specimen Z

Answer

Specimen X and Specimen Y share the greatest number of taxonomic categories because genus is the most specific shared rank among all pairs.
In the Linnaean classification system (Domain, Kingdom, Phylum, Class, Order, Family, Genus, Species), groups are arranged hierarchically from broadest to most specific. If two organisms belong to the same genus, they necessarily share every broader rank above it (family, order, class, phylum, kingdom, domain). Thus, the pair sharing a genus shares seven taxonomic levels, which is more than pairs sharing only a family or class.

Step-by-Step Solution

1
Recall the standard Linnaean classification hierarchy from broadest to most specific.
Domain → Kingdom → Phylum → Class → Order → Family → Genus → Species.
Taxonomic ranks are nested; organisms sharing a lower rank must share all higher ranks.
2
Evaluate the most specific shared taxonomic rank for each evaluated pair.
Specimens W and X share up to Class; Specimens Y and Z share up to Family; Specimens X and Y share up to Genus; Specimens W and Z share up to Class.
Identifying the deepest level of shared classification determines the total number of common taxonomic categories.
3
Compare the specificity of the shared ranks.
Genus is more specific than Family, Order, and Class.
Organisms sharing a genus share Domain, Kingdom, Phylum, Class, Order, Family, and Genus (7 shared ranks), indicating the closest evolutionary relationship.

Key Concept

Linnaean hierarchy rank ordering and nested taxonomic relationships
Estimated Time:1m 30s
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Topics

Taxonomy and Classification

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