Background: The question how evolution and speciation work is one of the major interests
of biology. Especially, genetic including karyotypic evolution within primates is of special interest
due to the close phylogenetic position of Macaca and Homo sapiens and the role as in vivo models in
medical research, neuroscience, behavior, pharmacology, reproduction and Acquired Immune Deficiency
Materials & Methods: Karyotypes of five macaque species from South East Asia and of one macaque
species as well as mandrill from Africa were analyzed by high resolution molecular cytogenetics to
obtain new insights into karyotypic evolution of old world monkeys. Molecular cytogenetics applying
human probes and probe sets was applied in chromosomes of Macaca arctoides, M. fascicularis, M.
nemestrina, M. assamensis, M. sylvanus, M. mulatta and Mandrillus sphinx. Established two- to multicolor-
fluorescence in situ hybridization (FISH) approaches were applied. Locus-specific probes,
whole and partial chromosome paint probes were hybridized. Especially the FISH-banding approach
multicolor-banding (MCB) as well as probes oriented towards heterochromatin turned out to be highly
efficient for interspecies comparison.
Conclusion: Karyotypes of all seven studied species could be characterized in detail. Surprisingly, no
evolutionary conserved differences were found among macaques, including mandrill. Between the
seven here studied and phenotypically so different species we expected several via FISH detectable
karyoypic and submicroscopic changes and were surprised to find none of them on a molecular cytogenetic
level. Spatial separation, may explain the speciation and different evolution for some of them,
like African M. sylvanus, Mandrillus sphinx and the South Asian macaques. However, for the partially
or completely overlapping habitats of the five studied South Asian macaques the species separation
process can also not be deduced to karyotypic separation.