Chromosomal Dynamics in Cercopithecini Studied by Williams-Beuren probe mapping

Chromosomal evolution in the tribe Cercopithecini and in related taxa is highly debated. Uncertaintyin reconstruction is mainly related to the great genetic variability and polymorphism of the taxa. Recentmolecular and karyological efforts individuate a split between genetically conservative, arbitrarily defi ned, “terrestrial”guenons and vervets, and genetically variable and derived “arboreal” guenons. We performed themapping of WS loci probe (7q11.23) in order to verify the chromosomal dynamics of the genomes of threetree-dwelling species of the tribe: C. neglectus, C. mitis mitis, C. albogularis labiatus. Data from literature for the“ground-dwelling” Chlorocebus aethiops sabaeus has been compared with our results.The distribution of the WS probe showed a high genomic dynamics in the different species, with three differentpattern of rearrangements. Starting from the ancestral synteny 7 found in Pongo pygmaeus (PPY), the presentmapping demonstrates different location of the hybridizations signals. A parsimonious interpretation lead to thehypothesis that a pericentric inversion transformed the PPY orthologous in C. neglectus. The C. mitis and thestrictly related C. a. labiatus demonstrate more complex, and derivative, rearrangements. According to the positionof the WS signal, and to banding pattern analysis, C. mitis and C. albogoularis, underwent to the pericentricinversion, followed by a paracentric inversion and a successive interstitial fi ssion that fragmented the synteny.Starting from the PPY like orthologous a single and independent event, a centric fi ssion, that did not affect theWS position, occurred in Ch. aethiops producing a Gorilla gorilla like chromosome.Our results confi rm the hypothesis that chromosomal dynamics in Cercopithecini proceed by fi ssions and inversionsand indicate the usefulness of the locus specifi c mapping approach for the identifi cation of intrachromosomerearrangements.