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Fig. 1 | Evolution: Education and Outreach

Fig. 1

From: Why Trees Are Important

Fig. 1

A hypothesis of relationships among gorillas, chimpanzees, and humans shown as two different, but complementary, tree graphs. a A phylogenetic tree. b A Hennig tree showing the identical genealogical relationships as (a) in alternative form. In (a), each lineage is traced back to a speciation event shown at each node. In (a), the ancestors (X and Y) are unsampled, encompass the entire lineage between speciation events, and represent only the minimum number of ancestors needed to account for descendant lineages. In (b), each ancestral lineage and descendant group is folded into a single node and the arrow lines represent statements of parent–child relationships, not lineages. In (b), speciation events are not shown but implied by the parent–child relationships. Two hypothetical synapomorphies uniting chimps and humans are placed on each tree graph. A similar mapping is shown in Hennig (1966)

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