Chromosome painting comparison of Leontopithecus chrysomelas (Callitrichine, Platyrrhini) with man and its phylogenetic position.

ABSTRACT

Using human probes of whole chromosomes, the homoeologies between human and Leontopithecus chrysomelas (Platyrrhini) karyotypes were established. Thirty-three conserved segments were observed between the two species. Intrachromosomal rearrangements between the two species were identified using hybridization of chromosome arm probes of human chromosomes 1 and 3. We also used chromosomal data to investigate phylogenetic relationships of Callitrichines. These data were encoded using Cebus capucinus , a species which kept fairly ancestral chromosomes, as reference. Two equi-parsimonious trees, including reversion or convergence events, were obtained. The monophyly of Callitrichines is confirmed. They share nine chromosomal rearrangements at least. The Cebuella-Callithrix group forms a clade sharing five rearrangements at least. According to the tree considered, the Tamarins, Leontopithecus and Saguinus share two chromosomal rearrangements restricted to these two taxa or none. Callimico accumulated seven chromosomal rearrangements unshared with other taxa, at least. To avoid convergence and reversion events, we propose the hypothesis of a network (or populational) evolution. Six chromosomal rearrangements would have occurred during the period of this network evolution. Finally, the karyotype of the last common ancestor to all Callitrichines has been reconstructed. It possessed 48 chromosomes.