Question

The phylogenetic tree of species A-G can be split into genera in many different ways. However, one of the options below is clearly invalid. Which one?

• A. Genus 1: ABC, Genus 2: DE, Genus 3: FG
• B. Genus 1: AB, Genus 2: CDE, Genus 3: FG
• C. Genus 1: A, Genus 2: BCDE, Genus 3: FG
• D. Genus 1: AB, Genus 2: CD, Genus 3: EFG

Answer 1

The correct option is D Genus 1: AB, Genus 2: CD, Genus 3: EFG

A phylogenetic tree is a diagram that represents evolutionary relationships among organisms. Phylogenetic trees are hypothetical, not definite facts. In trees, two species are more related if they have a more recent common ancestor and less related if they have a less recent common ancestor.
In this phylogenetic tree, possible species which can be paired together are any of A, B, C, D and E.


Here, the line leading up to the species F and G has diverged way earlier from the other species in the tree i.e., they have less recent common ancestor with other species. So, they can’t be put together in same genera along with other species (i.e. any of A, B, C, D and E), that makes genus 3: EFG invalid and hence, option d is the incorrect answer.