Classification groups organisms using shared features and evidence of relationships, including molecular sequences. Broad groups contain more specific groups. A binomial species name consists of a genus name followed by a specific epithet; the same genus indicates a closer classification than a shared family alone. Common names can vary between places, whereas scientific naming supports consistent communication.
A dichotomous key offers two contrasting choices at each step. Follow only the features stated, rather than guessing from habitat. In the biological species concept, reproductive isolation limits gene exchange between populations. Pre-zygotic barriers act before fertilisation, such as different mating seasons. Post-zygotic barriers act after fertilisation, such as low hybrid viability or fertility. This concept has limits for asexual organisms and fossils.
Example 1
Two animals are called Vulpes vulpes and Vulpes lagopus. Which named taxonomic group do they share?
They share the genus Vulpes but have different specific epithets, indicating different species.
Example 2
One key step reads “wings present →A; wings absent →B”. A specimen has no wings. Follow the key.
Choose B because the observed feature matches “wings absent”.
Watch out:The first word identifies genus. The full binomial is needed to identify the named species.
Classification, species and keys practice | Year 11 Biology | Ascent Arcade