Figure 16.7. A gene tree can have a different branching order from a species tree.

Figure 16.7A gene tree can have a different branching order from a species tree

In this example, the gene has undergone two mutations in the ancestral species, the first mutation giving rise to the ‘blue’ allele and the second to the ‘green’ allele. Random genetic drift in association with the two subsequent speciations results in the red allele lineage appearing in species A, the green allele lineage in species B and the blue allele lineage in species C. Molecular phylogenetics based on the gene sequences will reveal that the red-blue split occurred before the blue-green split, giving the gene tree shown on the right. However, the actual species tree is different, as shown on the left. Based on Li (1997).

From: Chapter 16, Molecular Phylogenetics

Cover of Genomes
Genomes. 2nd edition.
Brown TA.
Oxford: Wiley-Liss; 2002.
Copyright © 2002, Garland Science.

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