Chromosomal Polymorphism in Cercopithecini: Cytogenomics Provides Evidence for Reticulate Evolution and Incomplete Reproductive Isolation

• DOI: 10.1007/s10764-025-00483-5
• Publication Date: 2025-03-12T07:58:27Z
• Authors: Lauriane Cacheux; Michèle Gerbault-...; Peggy Motsch; Bertrand Bed’Hom; Florence Anne Ric...

Abstract Reticulate evolution is considered a widespread phenomenon in primates, as hybridization shaped evolutionary histories in all primate radiations, including Catarrhini. While genomic data suggest extensive ancient introgression among guenon lineages (tribe Cercopithecini), field and related genetic studies report extant hybridizations, along with fertility of guenon hybrids. By combining classical and molecular cytogenomics, we characterized chromosome organization for 12 guenon individuals, belonging to three species that associate in polyspecific groups: Cercopithecus cephus, C. nictitans and C. pogonias. Our results reveal multiple chromosomal heterozygosities in both the morphology of metaphase chromosomes and the molecular structure of centromeres, suggesting that chromosomal heterozygosity may be common in guenon genomes. Furthermore, we found similar chromosomal polymorphisms, involving similar chromosome and centromere variants, in distinct species. Our cytogenomic analysis also confirmed the hybrid origin of three individuals: two F1 hybrids between C. cephus and C. nictitans, and one backcross hybrid C. nictitans x (C. cephus x C. nictitans). Together, our results provide further possible evidence for reticulate evolution and incomplete reproductive isolation, and identify guenons as a good system to untangle the evolutionary dynamics of primate centromeres. This study provides a foundation for future research regarding the influence of hybridization on chromosomal reorganization, reproductive isolation, and speciation.