CYTOGENETIC STUDIES OF SMALL APE (HYLOBATIDAE) CHROMOSOMES
Roscoe Stanyon
Department of Evolutionary Biology, University of Florence, Italy;
e-mail: roscoe.stanyon@unifi.it
Each genus of small apes has a highly distinctive karyotype (karyomorph) at every level of cytogenetic analysis. Early workers using classical staining and banding had problems
integrating the karyolocial data with that of other primates. Chromosome painting allowed syntenic homology maps to be constructed for each of the four karyomorphs (2n = 38, 44,
50 and 52). They revealed that the great apes and Old World monkeys had strongly conserved karyotypes while those of small apes were highly rearranged. However, they provided
contradictory phylogenetic results to other bio-molecular tree of small ape evolution. More recently BAC-FISH investigations using a panel of about 900 BACs defined each breakpoint
by spanning or flanking BAC clones The syntenic map was refined and now includes small segments of homology which had previously gone undected, marker order (synteny block
orientation) and the location of ancestral and Evolutionarily New Centromeres. However, the BAC-FISH data similar to other biomolecular methods used up to now could not resolve
the phylogenetic tree of hylobatids. These difficulties may be explained by the rapid divergence of crown hylobatids, reticulate evolution and incomplete lineage sorting. The lack of
significant cytogenetic landmarks at the nodes of the gibbon tree could indicate that chromosomal rearrangements did not play a primary role in hylobatid speciation.
Key words: small apes, chromosomes, karyotype
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