Biology / Unit 1 Bio 0076 short lesson, about 20 seconds
Phylogenetic Tree
Captions available
The idea
A phylogenetic tree is a diagram showing the evolutionary relationships among species, with each internal branch point marking a common ancestor.
In practice
A branch splitting into two lineages marks the point where an ancestral population diverged into two separate species.
Where people slip
A tree's branch lengths, where shown, represent evolutionary distance or elapsed time — never a ranking of which species is more advanced.
Your place on the trail
Every lesson rests on earlier ones and opens later ones. Tap any to jump.
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