# Explain why cladistics may result in the reclassification of taxa that were previously grouped together under traditional Linnaean taxonomy.

> IB DP Biology Higher Level (2023 syllabus) — A3.2 Classification and cladistics · Explain · 4 marks

## Mark scheme (4 marks)

1. Traditional Linnaean classification groups organisms based on overall morphological similarity / overall resemblance, which can include analogous (homoplasious) characters.
2. Cladistics groups organisms exclusively by shared derived characters (synapomorphies) that indicate common ancestry.
3. If two organisms share a character due to convergent evolution rather than common ancestry, cladistics would place them in different clades, whereas Linnaean classification may have grouped them together.
4. Cladistics only recognises monophyletic groups (clades), so any taxon found to be paraphyletic or polyphyletic must be reclassified to reflect true evolutionary / phylogenetic relationships.

## Key terms

- [cladistics](https://www.gradenine.co.uk/glossary/cladistics)
- [Linnaean taxonomy](https://www.gradenine.co.uk/glossary/linnaean-taxonomy)

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Source: [GradeNine](https://www.gradenine.co.uk/q/explain-why-cladistics-may-result-in-54b65d4a) · Published by Druglandscape Ltd.