Fig. 8.

Evolutionary history of genesis of group B1 Sox paralogues as a consequence of multiple rounds of genomic duplication. “Vertebrate group B Sox prototypic composition” is hypothetical. Linkages of “Sox14 and Sox2” and “Sox21 and Sox1” are conserved in human and other primates, cow and chicken, but disrupted in mouse after extensive chromosomal rearrangements (Ensembl 50, July 2008; http://www.ensembl.org/index.html).³⁵⁾ Linkage of “Sox21 and Sox1” is found in a broader range of vertebrate species, e.g., dog, opossum, and medaka and other fish species, although this is disrupted in zebrafish. Linkages of “Sox14 and Sox2” is reported for platypus.⁴⁵⁾ Linkages of these genes in Xenopus genome have not been confirmed.