The Callimico goeldii (Primates, Platyrrhini) genome: karyology and middle repetitive (LINE-1) DNA sequences

Retrotransposon mapping in spider monkey genomes of the family Atelidae (Platyrrhini, Primates) shows a high level of LINE-1 amplification

To investigate the distribution of LINE-1 repeat sequences, a LINE-1 probe was Fluorescence In Situ Hybridized (FISH) on the chromosomes of Ateles geoffroyi and Ateles fusciceps (Atelidae); a LINE-1 probe was also mapped on Cebuella pygmaea (Cebidae) and used as an outgroup for phylogenetic comparison. Ateles spider monkeys have a highly rearranged genome and are an ideal model for testing whether LINE-1 is involved in genome evolution. The LINE-1 probe has been mapped in the two Atelidae species for the first time, revealing a high accumulation of LINE-1 sequences along chromosomal arms, including telomeres, and a scarcity of LINE-1 signals at centromere positions. LINE-1 mapping in C. pygmaea (Cebidae) revealed signals at centromere positions and along chromosome arms, which was consistent with previous published data from other Cebidae species. In a broader sense, the results were analyzed in light of published data on whole-chromosomal human probes mapped in these genomes. This analysis allows us to speculate about the presence of LINE-1 sequences at the junction of human chromosomal syntenies, as well as a possible link between these sequences and chromosomal rearrangements.

Phenotypic evolution in marmoset and tamarin monkeys (Cebidae, Callitrichinae) and a revised genus-level classification

Marmosets and tamarins (Cebidae, Callitrichinae) constitute the most species-rich subfamily of New World monkeys and one of the most diverse phenotypically. Despite the profusion of molecular phylogenies of the group, the evolution of phenotypic characters under the rapidly-emerging consensual phylogeny of the subfamily has been little studied, resulting in taxonomic proposals that have limited support from other datasets. We examined the evolution of 18 phenotypic traits (5 continuous and 13 discrete), including pelage, skull, dentition, postcrania, life-history and vocalization variables in a robust molecular phylogeny of marmoset and tamarin monkeys, quantifying their phylogenetic signal and correlations among some of the traits. At the family level, our resulting topology supports owl monkeys (Aotinae) as sister group of Callitrichinae. The topology of the callitrichine tree was congruent with previous studies except for the position of the midas group of Saguinus tamarins, which placement as sister of the bicolor group did not receive significant statistical support in both Maximum Parsimony and Bayesian Inference analyses. Our results showed that the highest value of phylogenetic signal among continuous traits was displayed by the long call character and the lowest was exhibited in the home range, intermediate values were found in characters related to osteology and skull size. Among discrete traits, pelage and osteology had similar phylogenetic signal. Based on genetic, osteological, pelage and vocalization data, we present an updated genus-level taxonomy of Callitrichinae, which recognizes six genera in the subfamily: Callimico, Callithrix, Cebuella, Mico, Leontopithecus and Saguinus. To reflect their phenotypic distinctiveness and to avoid the use of the informal "species group", we subdivided Saguinus in the subgenera Leontocebus, Saguinus and Tamarinus (revalidated here).

Multiple sex chromosome systems in howler monkeys (Platyrrhini, Alouatta)

In light of the multiple sex chromosome systems observed in howler monkeys (Alouatta Lacépède, 1799) a combined cladistic analysis using chromosomal and molecular characters was applied to discuss the possible origin of these systems. Mesoamerican and South American howlers were karyologically compared. FISH analysis using the chromosome painting probes for the #3 and #15 human chromosomes was applied to corroborate the homeology of the sexual systems. We found that the HSA3/15 syntenic association, present in the sex chromosome systems of South American Howlers, is not present in those of Mesoamerican ones. The autosomes involved in the translocation that formed the sexual systems in the Mesoamerican and South American species are different, thus suggesting an independent origin. Parsimony analysis resolved the phylogenetic relationships among howler species, demonstrating utility of the combined approach. A hypothesis for the origin of the multiple sex chromosome systems for the genus is proposed.

The systematics and evolution of New World primates - A review

This paper provides an overview of the taxonomy of New World primates from proposals of the 1980's based on morphology to the great number of studies based on molecular data aiming for the elucidation of the phylogeny of New World monkeys. The innovations of the first molecular phylogeny presented by Schneider et al. (1993) positioned Callimico as a sister group of Callithrix and Cebuella; Callicebus as a member of the pitheciids; Brachyteles as sister to Lagothrix; and the night monkeys (Aotus), capuchins (Cebus) and squirrel monkeys (Saimiri) in the same clade with the small callitrichines. These results were subsequently confirmed by dozens of subsequent studies using data from DNA sequences. Some issues difficult to resolve with the phylogenetic analyses of DNA sequences, such as the diversification of the oldest lineages (pitheciids, atelids and cebids), and the confirmation of Aotus as a member of the Cebinae clade (together with Cebus/Saimiri), were clarified with new molecular approaches based on the presence or absence of Alu insertions as well as through the use of phylogenomics. At this time, all relationships at the intergeneric level had been deciphered, with the exception of the definition of the sister group of callitrichines (whether Aotus or Cebus/Saimiri are sister to callitrichines, or if Aotus, Saimiri and Cebus form a clade together). Future studies should prioritize the alpha taxonomy of most Neotropical primate groups, and the use of phylogenetic and geographic data, combined with reliable estimates of divergence times, to clarify the taxonomic status at species and genus level, as well as to help understand the evolutionary history of this remarkable and highly diversified group.

Meiotic characterization and sex determination system of neotropical primates: Bolivian squirrel monkey Saimiri boliviensis (primates: Cebidae)

The chromosomal sex determination system differs among platyrrhine monkeys more than any other group of primates. Although a number of studies have investigated mitotic chromosomes across platyrrhine species, the meiotic chromosomes of many genera have not yet been described. The goal of this study was to characterize the sex determination system of Saimiri boliviensis. We described for the first time the meiotic cycle, confirming the sexual system in germ cells from testicular biopsies of four adult male S. boliviensis. All specimens were weighed and testicular volume was measured. We observed 22 bivalents corresponding to 2N = 44, and a "human-like" XY bivalent was found in diakinesis/metaphase I. In addition, mitotic studies from blood samples of both sexes were performed and G- and C-banding patterns agreed with previously reported karylogy of S. boliviensis boliviensis. Further meiotic studies should be performed in New World primates based on the great value of those studies for systematic evolutionary biology and conservation programs.

The primates of the Neotropics: genomes and chromosomes

The classification of neotropical primates has been controversial. Different arrangements have been proposed, depending on taxonomic criteria and on the traits selected for phylogenetic reconstructions. These include gross morphologic characters, karyotypic attributes and DNA sequence data of nuclear and mitochondrial genes and of repetitive genomic components. These approaches have substantially clarified the main intergeneric relationships although several intrageneric arrangements still remain to be elucidated. In this review, we compare karyologic and molecular data of this speciose group.

Phylogenetic relationships of the Callitrichinae (Platyrrhini, primates) based on beta2-microglobulin DNA sequences

The phylogenetic relationships of callitrichine primates have been determined by DNA sequence analyses of exons 1, 2, and 3 of the beta2-microglobulin gene. Parsimony, distance, and maximum likelihood analyses of ca. 900 base pairs of 21 taxa, representing all callitrichine genera, indicated that Saguinus was the most basal offshoot. Within Saguinus, S. fuscicollis appeared as the first divergent lineage followed by an unresolved trichotomy formed by S. mystax/S. imperator, S. midas/S. bicolor, and S. oedipus. A second callitrichine lineage was formed by Leontopithecus; each of the three species studied showed identical nucleotide sequences. Callimico appeared as the sister taxon of Callithrix/Cebuella. Genetic distances within this latter group were very small, although a stronger association between Cebuella and species of the Callithrix argentata group was observed. The inclusion of Cebuella in the genus Callithrix is suggested. These studies indicated that tamarins are more plesiomorphic than marmosets in agreement with the phyletic dwarfism hypothesis.

Proposed chromosomal phylogeny for the South American primates of the Callitrichidae family (Platyrrhini)

Cytogenetic and cytotaxonomic studies (G, C, sequential G/C, and NOR banding) were performed on 110 specimens representing the four genera of South American primates of the family Callitrichidae: Cebuella (C. pygmaea), Callithrix, groups argentata (C. argentata, C. emiliae, C. chrysoleuca, C. humeralifera, C. mauesi), and jacchus (C. aurita, C. geoffroyi, C. jacchus, C. kuhli, C. penicillata), Leontopithecus (L. chrysomelas, L. rosalia), and Saguinus (S. midas midas, S. m. niger). Mitotic chromosomes are characterized, and the rearrangements distinguishing the karyotypes of the taxa are inferred from arm homologies. The results were then converted into numerical data and submitted to cladistic analysis. The following conclusions were achieved: 1) Five karyotypic classes were observed, which correspond to the five taxa studied. Differences between them are as follows: a) Cebuella (2n = 44, 10 acrocentrics, A + 32 bi-armed autosomes, bi) and the argentata group (2n = 44, 10A + 32bi) are different from each other due to a reciprocal translocation; b) both can be distinguished from the jacchus group (2n = 46, 14A + 30bi) by a centric fusion/fission rearrangement and a paracentric inversion; c) Leontopithecus (2n = 46, 14A + 30bi) and Saguinus (2n = 46, 14A + 30bi) differ from the jacchus group by a reciprocal translocation and three paracentric inversions; and d) Saguinus is different from the others by one paracentric inversion and pericentric inversions in at least four pairs of acrocentric autosomes. 2) The cladistic analysis separates Cebus (used as an outgroup) from the Callitrichidae groups, which forms a clade. Among the Callitrichidae, marmosets (Cebuella and Callithrix) form a sub-clade, Cebuella and the argentata group being more closely related to each other than both are to the jacchus group. Tamarins (Leontopithecus and Saguinus) are also quite close, so that if one was not derived from the other, they with the marmosets share a common ancestor. Among the tamarins, Leontopithecus is karyotypically closest to the marmosets, specifically to the jacchus group. 3) Based on the chromosome information and considering the possible direction of the evolutionary changes (primitivity or phyletic dwarfism hypothesis, previously advanced by other authors), it was possible to propose the ancestral karyotypes and to develop two alternatives for the origin, differentiation and dispersion of the callitrichid. Both proposals are plausible, but when the geographical distribution is considered, the phyletic dwarfism hypothesis seems to be the most probable.

Molecular phylogeny of new world primates (Platyrrhini) based on beta2-microglobulin DNA sequences

Neotropical primates, traditionally grouped in the infraorder Platyrrhini, comprise 16 extant genera. Cladistic analyses based on morphological characteristics and molecular data resulted in topologic arrangements depicting disparate phylogenetic relationships, indicating that the evolution of gross morphological characteristics and molecular traits is not necessarily congruent. Here we present a phylogenetic arrangement for all neotropical primate genera obtained from DNA sequence analyses of the beta2-microglobulin gene. Parsimony, distance, and maximum likelihood analyses favored two families, Atelidae and Cebidae, each containing 8 genera. Atelids were resolved into atelines and pitheciines. The well-supported ateline clade branched into alouattine (Alouatta) and ateline (Ateles, Lagothrix, Brachyteles) clades. In turn, within the Ateline clade, Lagothrix and Brachyteles were well-supported sister groups. The pitheciines branched into well-supported callicebine (Callicebus) and pitheciine (Pithecia, Cacajao, Chiropotes) clades. In turn, within the pitheciine clade, Cacajao and Chiropotes were well-supported sister groups. The cebids branched into callitrichine (Saguinus, Leontopithecus, Callimico, Callithrix-Cebuella), cebine (Cebus, Saimiri), and aotine (Aotus) clades. While the callitrichine clade and the groupings of species and genera within this clade were all well supported, the cebine clade received only modest support, and the position of Aotus could not be clearly established. Cladistic analyses favored the proposition of 15 rather than 16 extant genera by including Cebuella pygmaea in the genus Callithrix as the sister group of the Callithrix argentata species group. These analyses also favored the sister grouping of Callimico with Callithrix and then of Leontopithecus with the Callithrix-Callimico clade.

Phylogenetic relationships of the New World monkeys (Primates, platyrrhini) based on nuclear G6PD DNA sequences

In order to test hypotheses about the phylogenetic relationships among living genera of New World monkeys, 1.3 kb of DNA sequence information was collected for two introns of the glucose-6-phosphate dehydrogenase (G6PD) locus, encoded on the X chromosome, for 24 species of New World monkeys. These data were analyzed using a maximum parsimony algorithm. The strict consensus of the three most-parsimonious gene trees that result shows support for the following clades: a pitheciine clade including Callicebus within which Chiropotes and Cacajao are sister taxa, an Alouatta-atelin clade within which Brachyteles is the sister taxon of Lagothrix and which is sister to another clade containing the callitrichines, and a callitrichine/Aotus/Cebus/Saimiri clade. Within the callitrichines, Callimico is the sister taxon of Callithrix. Cebus and Saimiri form a clade. These results are broadly consistent with previously published DNA sequence analyses of platyrrhine phylogeny and provide additional support for groupings provisionally proposed in those earlier studies. Nevertheless, questions remain as to the relative phylogenetic placement of Leontopithecus and Saguinus, the branching order within the Aotus/Cebus/Saimiri/callitrichine clade, and the placement of the pitheciine clade relative to the atelines and the callitrichines.

Chromosome painting defines genomic rearrangements between red howler monkey subspecies

We hybridized whole human chromosome-specific DNA libraries to chromosomes of two supposed subspecies of Alouatta seniculus: Alouatta seniculus sara and Alouatta seniculus arctoides. The number of hybridization signals per haploid set is 42 in A. s. sara and 43 in A. s. arctoidea; the two karyotypes differ by at least 16 chromosomal rearrangements, including numerous translocations. An unusual sex chromosome system is shared by both taxa. The sex chromosome system results from a Y translocation with a chromosome homologous to parts of human chromosome 3/15 and can be described as X1X2Y1Y2/X1X1X2X2 (male/female). Both red howlers also have microchromosomes, a highly unusual karyological trait not found in other higher primates. These microchromosomes are not hybridized by any human chromosome paint and therefore are probably composed of repetitive DNA. It is well known that New World monkeys have high karyological variability. It is probable that molecular cytogenetic analyses including chromosome painting will permit an accurate reconstruction of the phylogeny of these monkeys and help establish the ancestral karyotype for higher primates.

Molecular phylogeny of the New World monkeys (Platyrrhini, primates) based on two unlinked nuclear genes: IRBP intron 1 and epsilon-globin sequences

Nuclear sequences of the 1.8 kilobase (kb) long intron 1 of the interstitial retinol-binding protein gene (IRBP), previously determined for 11 of the 16 extant genera of New World monkeys (superfamily Ceboidea, infraorder Platyrrhini), have now been determined for the remaining 5 genera. The maximum parsimony trees found, first with IRBP sequences alone and then with tandemly combined IRBP and epsilon-globin gene sequences from the same species, supported a provisional cladistic classification with the following clusters. Subtribes Callitrichina (Callithrix, Cebuella), Callimiconina (Callimico), Leontopithecina (Leontopithecus) and Saguina (Saguinus) constitute subfamily Callitrichinae, and subfamilies Callitrichinae, Aotinae (Aotus), and Cebinae (Cebus, Saimiri) constitute family Cebidae. Subtribes Chiropotina (Chiropotes, Cacajao) and Pitheciina (Pithecia) constitute tribe Pitheciini; and tribes Pitheciini and Callicebini (Callicebus) constitute subfamily Pitheciinae. Subtribes Brachytelina (Brachyteles, Lagothrix) and Atelina (Ateles) constitute tribe Atelini, and tribes Atelini and Alouattini (Alouatta) constitute subfamily Atelinae. The parsimony results were equivocal as to whether Pitheciinae should be grouped with Atelinae in family Atelidae or have its own family Pitheciidae. The cladistic groupings of extant ceboids were also examined by different stochastic evolutionary models that employed the same stochastic process of nucleotide substitutions but alternative putative phylogenetic trees on which the nucleotide substitutions occurred. Each model, i.e., each different tree, predicted a different multinomial distribution of nucleotide character patterns for the contemporary sequences. The predicted distributions that were closest to the actual observed distributions identified the best fitting trees. The cladistic relationships depicted in these best fitting trees agreed in almost all cases with those depicted in the maximum parsimony trees.

Comparative karyology and evolution of the Amazonian Callithrix (Platyrrhini, Primates)

Chromosomal studies in three species of Amazonian Callithrix (2n=44) and data in the literature show that this group is karyomonotypic. Moreover, it is characterized by the presence of abundant heterochromatic regions, unlike the situation in congeneric forms of Callithrix of the Atlantic coast with 2n=46, and by the presence of a highly repetitive, exclusive DNA component, with a basic repeat motif of 1528bp. Karyotypic comparisons with other Callitrichids and an outgroup species showed that Callitrichids are karyologically conserved and explained several rearrangements that had presumably occurred during their phyletic radiation. Analyses of karyologic data enabled the construction of two alternative phylogenetic topologies. The lack of derived homoeologies, common to all members of the genus Callithrix grouped at present, and the fact that Amazonian species were more similar to Cebuella pygmaea (2n=44) than to their congeneric forms with 2n=46 suggested that species at present included in the Amazonian Callithrix should be grouped with C. pygmaea.

Satellite DNA sequences in the New World primate Cebus apella Plaatyrrhini, Primates)

Two satellite DNAs, designated CapA and CapB, were isolated from the neotropical primate, Cebus apella. The satellites exhibit nonoverlapping distributions on C. apella chromosomes. CapA is a major component of interstitial regions of constitutive heterochromatin, a very large block of heterochromatin comprising most of the long arm of chromosome 11, and some telomeres. The CapA monomer has a length of about 1500 bp and appears recently to have undergone an amplification episode in the C. apella genome. CapA-like sequences are probably present in members of the family Cebidae (to which C. apella belongs), but not in members of the family Callitrichidae (marmosets). CapB sequences can be detected at the centromeres of many C. apella chromosomes, and similar sequences are present in all neotropical primates. The 342 bp CapB monomer shares 60%-64% sequence identity with several alpha satellite sequences of human origin. Because of its structure, sequence, and location, it appears that CapB is the New World primate homolog of Old World primate alpha satellite DNA.

Satellite DNA sequences in the neotropical marmoset Callimico goeldii (Primates, Platyrrhini)

Two families of tandemly repeated satellite DNAs were isolated from the neotropical primate Callimico goeldii (Goeldi's marmoset). One satellite, CgoA, is over 70% A + T and has a monomer length of 338 bp. The other satellite, CgoB, is 50% A + T and has a monomer length of 916 bp. Both CgoA and CgoB hybridize strongly with Callimico DNA, but not with the DNA of other new and old world primates. Based upon a neutral substitution rate of 1.5 X 10(-9)/site per year for primates, sequence data from 15 CgoA monomers indicate that the tandem array is at least 30 million years old. Since no other neotropical primate has amplified CgoA sequences, the data suggest that the ancestor of Callimico separated from the other neotropical primates at least 30 million years ago. This value is about fourfold larger than the value of 7-9 million years derived from immunological data by Sarich and Cronin (1980). Possible reasons for this discrepancy are discussed.