Can mitochondrial DNA, nuclear microsatellite DNA and cranial morphometrics accurately discriminate different Aotus species (Cebidae)? Some insights on population genetics parameters and the phylogeny of the night monkeys

We investigated the use of diverse procedures to discriminate among Aotus taxa (Aotus; Cebidae, Platyrrhini) and provide new insights about the systematics and phylogenetic relationships of Aotus taxa. To carry out these tasks we measured 38 craniometric characters in 80 individuals representing eight Aotus taxa. We sequenced 190 specimens at the mitochondrial COII gene for all 13 Aotus taxa recognized to date as well as genotyped (12 nuclear DNA microsatellites) 143 individuals belonging to seven Aotus taxa. The use of skull morphometrics allowed us to differentiate the most southern of the taxa analyzed, Aotus azarae boliviensis. Microsatellite analyses in combination with the FST statistic, gene flow and AMOVA analyses also significantly differentiated A. a. boliviensis. The use of morphometrics and microsatellites did not clearly differentiate A. nancymaae (a red-necked taxon) from all of the other gray-necked Aotus taxa at the northern side of the Amazon River. However, the other more southern Aotus taxa were not included (A. nigriceps, A. infulatus and A. a. azarae) in these analyses. Microsatellites did not detect any significant bottleneck in the three taxa with the highest sample sizes (A. nancymaae, A. vociferans and A. lemurinus griseimembra). The mitochondrial analyses revealed a higher discrimination power than the other two procedures. Two large clusters were found with two relevant sub-clusters inside each one of them: A. nancymaae + A. miconax and all the Northern Amazon taxa (excluding A. trivirgatus) on one side, and A. trivirgatus and all the other Southern Amazon taxa on the other side. In the Northern Aotus group, the morphological and molecular differentiation is very small but the chromosome differentiation is outstanding. This indicates that the fundamental processes for diversification are parapatric chromosomal events (more than peripatric or stasipatric chromosomal events) following fision processes from 2n = 46, 47, 48 (A. vociferans) to 2n = 58 (A. l. lemurinus). Taking all of the data into account we propose that within Aotus, four superspecies could be defined: 1- A. vociferans with six karyomorphs, including vociferans, brumbacki, jorgehernandezi, griseimembra, lemurinus and zonalis; 2- A. trivirgatus, although we are fairly ignorant about this taxon; 3- A. miconax, including A. miconax and A. nancymaae, although we don't know the karyotype of the original A. miconax and 4- A. azarae with diverse karyomorphs (less differentiated than in A. vociferans), including nigriceps, azarae, boliviensis and infulatus.