Chapter 27: Phylogenetic Reconstruction: Figure 27.32 - Sequence similarity does not always accurately represent relatedness.

Figure 27.32 - Sequence similarity does not always accurately represent relatedness.

Figure 27.32. Sequence similarity does not always accurately represent relatedness. In this hypothetical tree, the evolution of three species is indicated by thick light blue bars and the evolution of specific genes is indicated by thin red and blue lines within the bars. An early gene duplication gave rise to the α and β genes; thus all of the α genes are paralogs of the β genes. Over time, the α and β genes diverged such that their functions now differ (indicated by red and blue). The multiple forms of the α genes arose through speciation events, and thus all are orthologs of each other (and likewise for all the β genes). If species 3 had a slower rate of evolution than the other two, then the α and β paralogs within species 3 will be more similar to each other (as measured by summing the branch lengths connecting them) than either is to their orthologs in other species. (Redrawn from Eisen J.A. Genome Res. 8: 163–167, Table 4, © 1998 CSHLP.)

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