Molecular phylogenetics of howler monkeys (Alouatta, Platyrrhini)

Abstract.

Molecular phylogenetic analyses of seven Brazilian Alouatta species, based on cytochrome b DNA sequence data were carried out. Parsimony and neighbor joining topologies grouped Alouatta belzebul and A. fusca as sister groups in one clade while another, well-supported clade contained A. seniculus as the most basal offshoot, followed by A. nigerrima as a sister lineage of A. macconnelli/A. stramineus. Estimates of inter-specific sequence divergence were generally low, and estimates of the time of divergence indicated that the main Alouatta lineages emerged during a short evolutionary interval. A comparison with karyotypic data confirmed the molecular topology showing a closer relationship between A. macconnelli and A. stramineus in respect to A. nigerrima. It also showed that the XX/XY sex chromosome system was maintained in several lineages while the X₁X₂Y/X₁X₁X₂X₂ system appeared independently at least three times during the radiation of howler monkeys. Moreover, the X₁X₂Y₁Y₂/X₁X₁X₂X₂ system might have appeared once or, alternatively, twice and independently.