Chromosomal Evolution of Gibbons (Hylobatidae)

This chapter discusses the evolutionary aspects of chromosomal genome organization in gibbons (Hylobatidae, lesser or small apes), which, together with the great apes and humans, are included in the superfamily Hominoidea. Each of the four recognized gibbon genera shows a different karyomorph, with chromosome numbers ranging between 2n = 38 in the hoolock gibbon and 2n = 52 in the white-cheeked gibbon. An overview is provided about the dramatic lineage-specific chromosomal rearrangements in gibbons, which is unparalleled among primates. We further review the reported chromosomal differences observed between the four genera, present the inferred ancestral gibbon karyotype, and highlight recent attempts to reconstruct a gibbon chromosomal phylogeny. Finally, present knowledge on the molecular structure of evolutionary chromosome breakpoints, on the nuclear genome organisation, as well as on genomic and epigenomic changes in this group of higher primates, is summarized.