A morphological study and the variability in the number of infraorbital foramina in the African green monkey (Grivet) (Chlorocebus aethiops) using microcomputed tomography

Knowledge of the nonhuman primate morphology and anatomy related to craniofacial mechanoreception is essential for a fundamental understanding of the incidents that have occurred during the evolution of craniofacial features. The present study focuses on the variability in the number of infraorbital foramina and associated anatomical structures such as the infraorbital canal (IOC) and the infraorbital groove (IOG), as they are considered to play an important role in the behavioral ecology of these animals. A total of 19 skulls of Chlorocebus aethiops were analyzed. The number of infraorbital foramina was assessed macroscopically using a magnifying glass and a small diameter probe. Three dimensional (3D) projections and morphometric analysis of the infraorbital foramina, IOCs, and IOGs were performed using microcomputed tomography (micro-CT) for two skulls that represent one of the most common morphological types. Regardless of sex and body side, the most common morphological type observed in the studied species is the presence of three infraorbital foramina. The IOC takes a funnel or pinched shape. 3D projections were made to assess the course of the infraorbital vascular and nerve bundles in selected individuals. The results indicate a high morphological diversity within the species, although there appears to be a consistent distribution pattern of infraorbital neurovascular bundles in species of the Cercopithecidae family. The use of X-ray micro-CT allowed 3D visualization of the maxillary region to determine the variability of the infraorbital foramina and to track the division of the infraorbital neurovascular bundle in the case of the most common macroscopic expression of the number of the infraorbital foramen in C. aethiops, as well as the morphometric of the IOCs and IOGs which are related to mechanoreception of the primate's snout.

The earliest most complete skeleton of Theropithecus

The middle Pliocene site of Woranso-Mille in the Afar Region of Ethiopia has yielded numerous significant early hominin fossils representing multiple, coexisting taxa. Here we report on another significant discovery, the oldest partial skeleton of the papionin, Theropithecus. The specimen was recovered from the Aralee Issie collection area over multiple field seasons from 2004 through 2019. The specimen was unearthed in situ from the fluvial facies of the Mesgid Dora Tuff dated to 3.66-3.57 Ma. The partial skeleton, ARI-VP-1/26, is that of a subadult male lacking a skull. In the absence of unambiguously associated craniodental remains, the male status of the specimen was established from the dimensions of the long bones in comparison to those of other Theropithecus from Woranso-Mille. ARI-VP-1/26 is noteworthy because it preserves partial hand and foot skeletons, including a complete set of metacarpals from the left side. The theropith status of ARI-VP-1/26 was established based on the detailed anatomy of the postcranial skeleton, especially the proximal and distal humerus, proximal radius, and proximal femur. The morphology of the postcranium of ARI-VP-1/26 is consistent with that of recognized Theropithecus from Woranso-Mille and, specifically, with specimens recognized as Theropithecus oswaldi cf. darti from other sites. The ratio of the lengths of the first metacarpal to metacarpals 2-5 in ARI-VP-1/26 is intermediate between that seen in extant Papio and Theropithecus. In Theropithecus gelada and Theropithecus brumpti, the pairing of pollical and indical metacarpals of near equal length contributes to the species' high opposability index and is associated with a 'manual grazing' feeding habit. Cercopithecids constitute 43% of the identified vertebrates at Aralee Issie, and T. oswaldi cf. darti is the most common mammalian species. The monkeys of Aralee Issie lived in an open shrubland habitat, but the specific reasons for their high prevalence at the site are unclear.

Gene Content and Coding Diversity of the Growth Hormone Loci of Apes

The growth hormone (GH) locus has experienced a dramatic evolution in primates, becoming multigenic and diverse in anthropoids. Despite sequence information from a vast number of primate species, it has remained unclear how the multigene family was favored. We compared the structure and composition of apes' GH loci as a prerequisite to understanding their origin and possible evolutionary role. These thorough analyses of the GH loci of the chimpanzee, gorilla, and orangutan were done by resorting to previously sequenced bacterial artificial chromosomes (BACs) harboring them, as well as to their respective genome projects data available in GenBank. The GH loci of modern man, Neanderthal, gibbon, and wild boar were retrieved from GenBank. Coding regions, regulatory elements, and repetitive sequences were identified and compared among species. The GH loci of all the analyzed species are flanked by the genes CD79B (5') and ICAM-1 (3'). In man, Neanderthal, and chimpanzee, the loci were integrated by five almost indistinguishable genes; however, in the former two, they rendered three different hormones, and in the latter, four different proteins were derived. Gorilla exhibited six genes, gibbon seven, and orangutan four. The sequences of the proximal promoters, enhancers, P-elements, and a locus control region (LCR) were highly conserved. The locus evolution might have implicated duplications of the ancestral pituitary gene (GH-N) and subsequent diversification of the copies, leading to the placental single GH-V gene and the multiple CSH genes.

Feeding ecology of the last European colobine monkey, Dolichopithecus ruscinensis

Currently, very little is known about the ecology of extinct Eurasian cercopithecids. Dietary information is crucial in understanding the ecological adaptations and diversity of extinct cercopithecids and the evolution of this family. For example, the colobine genus Dolichopithecus is represented by multiple large-bodied species that inhabited Eurasia during the Pliocene-Early Pleistocene. The available evidence, though limited, suggests semiterrestrial locomotion, which contrasts with most extant African and Asian colobines that exhibit morphological and physiological adaptations for arboreality and folivory. These differences raise questions regarding the dietary specialization of early colobine taxa and how/if that influenced their dispersion out of Africa and into Eurasia. To further our understanding of the ecology of Plio-Pleistocene cercopithecids, we characterized the dental capabilities and potential dietary adaptations of Dolichopithecus ruscinensis through dental topographic and enamel thickness analyses on an M¹ from the locality of Serrat d'en Vacquer, Perpignan (France). We also assessed the feeding behavior of D. ruscinensis through dental microwear texture analysis on a broad sample of fossil molars from fossil sites in France, Greece, Bulgaria, and Romania. Dental topographic and enamel thickness analyses suggest that D. ruscinensis could efficiently process a wide range of foods. Results of the dental microwear texture analysis suggest that its diet ranged from folivory to the consumption of more mechanically challenging foods. Collectively, this suggests a more opportunistic feeding behavior for Dolichopithecus than characteristic of most extant colobines.

Macronutrient composition of olive baboon (Papio anubis) milk: A comparison to rhesus macaque (Macaca mulatta) milk

This study was designed to (1) characterize the macronutrient composition of olive baboon (Papio anubis) milk, (2) compare baboon milk composition to that of rhesus macaques (Macaca mulatta), and (3) evaluate the association between the proportion of milk energy derived from protein and relative growth rate within anthropoid primates. A single milk sample was collected from each of eight lactating olive baboons ranging between 47- and 129-days postparturition and six rhesus macaques from 15- to 92-days living at the same institution under identical management conditions. Macronutrient composition (water, fat, protein sugar, and ash) was determined using standard techniques developed at the Nutrition Laboratory at the Smithsonian National Zoological Park. Baboon milk on average contained 86.0% ± 0.6% water, 4.7% ± 0.5% fat, 1.6% ± 0.04% protein, 7.3% ± 0.07% sugar, and 0.165% ± 0.007% ash. Baboon milk gross energy (GE) averaged 0.81 ± 0.04 kcal/g with 51.9% ± 2.6% from fat, 11.8% ± 0.7% from protein, and 36.2% ± 2.0% from sugar. Baboon milk demonstrated strong similarity to milk composition of the closely phylogenetically related rhesus macaque (86.1% ± 0.3% water, 4.1% ± 0.4% fat, 1.69% ± 0.05% protein, 7.71% ± 0.08% sugar, 0.19% ± 0.01% ash, and 0.78 kcal/g). There was no statistical difference between baboon and macaque milk in the proportions of energy from fat, sugar, and protein. Baboon milk can be described as a high sugar, moderate fat, and low protein milk with moderate energy density, which is consistent with their lactation strategy characterized by frequent, on-demand nursing and relatively slow life history compared to nonprimate mammal taxa. The milk energy from protein of both baboon and macaque (12.8% ± 0.3%) milk was intermediate between the protein milk energy of platyrrhine (19.3%-23.2%) and hominoid (8.9%-12.6%) primates, consistent with their relative growth rates also being intermediate. Compared to these cercopithecid monkeys, platyrrhine primates have both higher relative growth rates and higher milk energy from protein, while apes tend to be lower in both.

An assessment of the postcranial skeleton of the Paracolobus mutiwa (Primates: Colobinae) specimen KNM-WT 16827 from Lomekwi, West Turkana, Kenya

The postcranium of a large-bodied colobine monkey attributed to Paracolobus mutiwa from the site of Lomekwi, West Turkana, Kenya, is described. The partial skeleton (KNM-WT 16827) was recovered from locality LO 1, dated to 2.58-2.53 Ma, and preserves postcranial elements including fragments of scapula, humerus, proximal ulna, proximal radius, os coxae, proximal femur, astragalus, and calcaneus. KNM-WT 16827 was identified as P. mutiwa based on cranial similarities to the holotype female maxilla (KNM-ER 3843) and the holotype of Paracolobus chemeroni (KNM-BC 3), but is currently the only specimen of this taxon with associated cranial and postcranial elements. The skeleton is morphologically distinct from other large cercopithecid specimens from the Turkana Basin, including several assigned to Cercopithecoides williamsi, Cercopithecoides kimeui, Rhinocolobus turkanaensis, and Theropithecus oswaldi and differs from KNM-BC 3 in the larger cranium and shorter and more robust long bones. KNM-WT 16827 has forelimb and hindlimb features exhibiting a mixture of traits more associated with terrestrial locomotor behavior, including robust humeral deltoid tuberosity, retroflexed humeral medial epicondyle, deep ulnar trochlear notch, relatively short lower iliac height, prominent femoral greater trochanter, asymmetrical astragalar trochlea, and weak digit flexor grooves on the calcaneus. KNM-WT 16827 is also proportionally distinct from KNM-BC 3 and other Turkana Basin specimens attributed to large-bodied taxa such as C. williamsi, C. kimeui, R. turkanaensis, and T. oswaldi in having relatively shorter limbs and smaller tarsals. The traits shared with P. chemeroni and other extinct taxa are either typical for colobines, or likely due to P. mutiwa and P. chemeroni sharing adaptations for terrestrial locomotion relative to extant colobinans. Although a full cranial assessment is needed, based on its postcranial morphology KNM-WT 16827 is distinct from KNM-BC 3, C. williamsi, R. turkanaensis, Theropithecus, and extant colobines, warranting further analyses to better assess the taxonomic assignment of the specimen.

New mitogenomic lineages in Papio baboons and their phylogeographic implications

OBJECTIVES

Incomplete and/or biased sampling either on a taxonomic or geographic level can lead to delusive phylogenetic and phylogeographic inferences. However, a complete taxonomic and geographical sampling is often and for various reasons impossible, particularly for widespread taxa such as baboons (Papio spp.). Previous studies on baboon phylogeography identified several sampling gaps, some of which we fill by investigating additional material including samples from museum specimens.

MATERIALS AND METHODS

We generated 10 new mitochondrial genomes either via conventional PCR and subsequent Sanger sequencing from two blood samples or via high-throughput shotgun sequencing from degraded DNA extracted from eight museum specimens. Phylogenetic relationships and divergence times among baboon lineages were determined using maximum-likelihood and Bayesian inferences.

RESULTS

We identified new mitochondrial lineages in baboons from Central Africa (Chad, the Central African Republic), from the Mahale, and the Udzungwa Mountains (Tanzania), with the latter likely representing a case of mitochondrial capture from sympatric kipunjis (Rungwecebus kipunji). We also found that the mitochondrial clades of olive baboons found in Ivory Coast and Tanzania extend into Niger and the Democratic Republic of Congo, respectively. Moreover, an olive baboon from Sierra Leone carries a mitochondrial haplotype usually found in Guinea baboons, suggesting gene flow between these two species.

DISCUSSION

The extension of the geographic sampling by including samples from areas difficult to visit or from populations that are most likely extirpated has improved the geographic and temporal resolution of the mitochondrial phylogeny of baboons considerably. Our study also shows the great value of museum material for genetic analyses even when DNA is highly degraded.

Patterns and magnitudes of craniofacial covariation in extant cercopithecids

The cranium contains almost all of the vertebrate sensory organs and plays an essential role in vertebrate evolution. Research on the primate cranium has revealed that it is both highly integrated and modular, but studies have historically focused on covariance between the neurocranium and facial skeleton rather than on bones specific to special senses such as vision. The goal of this work is to investigate patterns and magnitudes of craniofacial covariation in extant cercopithecids with particular attention to the orbits. This study takes a quantitative approach using data collected from 38 homologous cranial landmarks across 11 genera of cercopithecid monkeys (Cercopithecidae, N = 291). These data demonstrate that both patterns and magnitudes of craniofacial covariation differ across Cercopithecidae at subfamily, tribe, and genus levels, with the strongest integration in the papionins (and specifically Papio) and significantly weaker covariation in the colobines, particularly Presbytis. Orbital height does not covary with other measurements of the cranium to the same degree as other cranial traits in Cercopithecidae and is highly constrained across the family. This study has important implications for our understanding of the evolution and development of morphological diversity in the cercopithecid cranium and evolution of the primate eye. This study also highlights the potential error of broad assumptions about generalizing patterns and magnitudes of modularity and integration across primates. Additionally, these findings reiterate the importance of trait selection for interpreting fossil taxonomy, as craniofacial covariation may impact phenotypes commonly used to differentiate fossil primate species.

First record of Theropithecus (Cercopithecidae) from the Republic of Djibouti

We describe here several specimens of the genus Theropithecus from the southern shore of Lake Assal in the Republic of Djibouti; they are the first record of the genus from this country. We assign them to a derived stage of T. oswaldi. This identification has implications for the age of the informal 'Formation 1' from this area, which should probably be assigned to the Middle Pleistocene. In addition, the presence of T. oswaldi close to the Bab el Mandeb Strait strongly suggests that the species followed this route to India, rather than a more northern one.

Mesopithecus pentelicus from the Turolian locality of Kryopigi (Kassandra, Chalkidiki, Greece)

New material of the Mio-Pliocene colobine Mesopithecus from the Turolian locality of Kryopigi (Greece) is described here. It includes a complete skull with the atlas attached and other dental and postcranial elements representing at least five individuals (four males and one female). The material is compared with Mesopithecus delsoni, Mesopithecus pentelicus, Mesopithecus monspessulanus and intermediate forms from more than a dozen Turolian localities of the Greco-Iranian province. These comparisons support the attribution of the Kryopigi material to M. pentelicus. The chronostratigraphic distribution of Mesopithecus species and intermediate forms suggests that the Kryopigi fauna could be dated as younger than the Perivolaki locality with M. delsoni/pentelicus (7.1-7.3 Ma, MN12) and older than the Dytiko localities with M. aff. pentelicus, M. cf. pentelicus and M. cf. monspessulanus (?middle MN13). The dimensions of the atlas are within the distribution of extant colobines. The skull shows bite-marks, probably caused by the hyaena Adcrocuta eximia.

Complete mitochondrial genome of a Toque Macaque (Macaca sinica)

The Toque macaque (Macaca sinica) is the only macaque species on Sri Lanka and endemic to the island. The newly generated mitochondrial genome (Genbank accession number MG870385), obtained from a captive individual, has a length of 16,525 bp and exhibits the typical structure of mammalian mitochondrial genomes. Phylogenetically, the Toque macaque is nested within the Macaca sinica species group and represents a sister lineage to a M. assamensis/M. thibetana clade. The new data help to further illuminate and better understand the complex phylogeny of macaques.

Complete mitochondrial genome of an olive baboon (Papio anubis) from Gombe National Park, Tanzania

The olive baboon (Papio anubis) is the most widely distributed baboon species. We report here on the complete mitochondrial genome of an olive baboon from the south-eastern edge of the species' range from Gombe National Park (NP), Tanzania. The genome (GenBank accession number MG787545) has a length of 16,490 bp and exhibits the typical structure of mammalian mitochondrial genomes. Phylogenetically, the olive baboon from Gombe NP is most closely related to eastern P. anubis, northern P. cynocephalus and P. hamadryas. The data are an important addition to further clarify the phylogeography of baboons and phylogeny of papionins in general.

Functional evolution of the OAS1 viral sensor: Insights from old world primates

Infections with viral pathogens impose considerable selective pressure on host defensive genes. Those genes at the forefront, responsible for identifying and binding exogenous molecular viral components, will carry the hallmarks of this struggle. Oligoadenylate synthetase (OAS) enzymes play a major role in the innate defense against a large number of viruses by acting as sensors of viral infections. Following their up-regulation by the interferon pathway, OASs bind viral dsRNA and then signal ribonuclease L (RNase L) to degrade RNA, shutting down viral and host protein synthesis. We have investigated the evolution of OAS1 in twenty-two Old World monkey species. We identified a total of 35 codons with the earmarks of positive selection and we performed a comprehensive analysis of their functional significance using in silico modeling of the OAS1 protein. Subdividing OAS1 into functional domains revealed intense purifying selection in the active domain but significant positive directional selection in the RNA-binding domain (RBD), the region where OAS1 binds viral dsRNA. The modeling analysis revealed a concentration of rapidly evolving residues in one region of the RBD suggestive of the sub-functionalization of different regions of the RBD. This analysis also identified several positively selected residues circumscribing the entry to the active site suggesting adaptive evasion of viral antagonism and/or selection for production of oligoadenylate of different length.

The complete mitochondrial genome of the drill (Mandrillus leucophaeus)

The drill (Mandrillus leucophaeus) is a primate of the family Cercopithecidae (Old World monkeys). Drills are among Africa's most endangered mammals, and are listed by the IUCN as the highest conservation priority of all African primates and are used as a model for cytomegalovirus vaccine and antiviral development. Here, we describe the complete mitochondrial genome (mitogenome) sequence of M. leucophaeus. The genome is 16 547 bp in length, comprising 13 protein-coding genes, 22 tRNAs, 2 rRNAs and a major non-coding region. The gene content and order is in accord with the common vertebrate form. All PCGs share the start codon ATG except ND2(ATC), ND3(ATT) and ND5(ATA). ND1, ND2 and ATP8 use ATG as the end codon. COX1, COX2, ATP6, ND4L and ND5 employ ATT as the end codon. The other five PCGs share the end codon T--. Phylogenic tree was constructed based on the complete mitogenome of M. leucophaeus and 12 closely related species to estimate their phylogenic relationship. We present an important genetic resource for the family Cercopithecidae in general.

Effect of age and sex on bone markers in Chlorocebus aethiops raised in captivity

BACKGROUND

The objective was to evaluate the procollagen type I N-propeptide (PINP), osteocalcin (OC), β-crosslaps (β-CTX), and parathyroid hormone (PTH) in relation to age and sex of Chlorocebus aethiops in captivity.

METHODS

Seventy-three monkeys were divided into four age groups: AG1 (juvenile); AG2 (young adult); AG3 (adult); and AG4 (senile). An electrochemiluminescence immunoassay with an Elecsys 2010 analyzer was used to determine the serum markers of bone.

RESULTS AND CONCLUSIONS

Sex did not influence the results of the markers. However, the variables PINP, OC, and β-CTX were negatively correlated with age (r = -0.643; r = -0.711; r = -0.488; P < 0.001, respectively), and PTH was correlated positively with age (r = 0.418, P < 0.001). The data obtained can be used as biomarkers of bone metabolism reference intervals in healthy C. aethiops in captivity.

First discovery of colobine fossils from the Late Miocene/Early Pliocene in central Myanmar

Here we report two kinds of colobine fossils discovered from the latest Miocene/Early Pliocene Irrawaddy sediments of the Chaingzauk area, central Myanmar. A left mandibular corpus fragment preserving M1-3 is named as a new genus and species, Myanmarcolobus yawensis. Isolated upper (M(1)?) and lower (M2) molars are tentatively identified as Colobinae gen. et sp. indet. Although both forms are medium-sized colobines, they are quite different from each other in M2 morphology. The isolated teeth of the latter show typical colobine-type features, so it is difficult to identify their taxonomic position, whereas lower molars of Myanmarcolobus have unique features, such as a trapezoid-shaped long median lingual notch, a deeply concave median buccal cleft, a strongly developed mesiobuccal notch, and rather obliquely running transverse lophids. Compared with fossil and living Eurasian colobine genera, Myanmarcolobus is most similar in lower molar morphology to the Pliocene Dolichopithecus of Europe rather than to any Asian forms. In Dolichopithecus, however, the tooth size is much larger and the median lingual notch is mesiodistally much shorter than that of Myanmarcolobus. The discovery of Myanmarcolobus in central Myanmar is the oldest fossil record in Southeast Asia not only of colobine but also of cercopithecid monkeys and raises many questions regarding the evolutionary history of Asian colobine monkeys.

Costs of mate-guarding in wild male long-tailed macaques (Macaca fascicularis): physiological stress and aggression

Mate-guarding is an important determinant of male reproductive success in a number of species. However, it is known to potentially incur costs. The aim of the present study was to assess the effect of mate-guarding on male physiological stress and aggression in long-tailed macaques, a species in which males mate-guard females to a lesser extent than predicted by the Priority of Access model (PoA). The study was carried out during two mating periods on three groups of wild long-tailed macaques in Indonesia by combining behavioral observations with non-invasive measurements of fecal glucocorticoid (fGC) levels. Mate-guarding was associated with a general rise in male stress hormone levels but, from a certain threshold of mate-guarding onwards, increased vigilance time was associated with a decrease in stress hormone output. Mate-guarding also increased male-male aggression rate and male vigilance time. Overall, alpha males were more physiologically stressed than other males independently of mating competition. Increased glucocorticoid levels during mate-guarding are most likely adaptive since it may help males to mobilize extra-energy required for mate-guarding and ultimately maintain a balanced energetic status. However, repeated exposure to high levels of stress over an extended period is potentially deleterious to the immune system and thus may carry costs. This potential physiological cost together with the cost of increased aggression mate-guarding male face may limit the male's ability to mate-guard females, explaining the deviance from the PoA model observed in long-tailed macaques. Comparing our results to previous findings we discuss how ecological factors, reproductive seasonality and rank achievement may modulate the extent to which costs of mate-guarding limit male monopolization abilities.

Identification of a derived dental trait in the papionini relative to other old world monkeys

Variation in the shape of teeth provides an immense amount of information about the evolutionary history and adaptive strategy of a mammalian lineage. Here, we explore variation in the expression of a purported molar lingual remnant (the interconulus) across the Old World Monkeys (Primates: Cercopithecidae) with the aim of elucidating a component of the adaptive radiation of this family. This radiation is characterized by a wide geographic range (Asia and Africa) as well as diverse dietary niches. While all of the cercopithecids are distinguished by their derived bilophodont molars, the colobines have evolved taller and more pointed cusps compared with the cercopithecines. We investigate whether the interconulus also correlates with phylogenetic affinity and/or dietary adaptation. We assess the frequency and range of interconulus expression in 522 specimens representing seven species of Old World Monkeys (Cercopithecus mitis, n = 78; Macaca fascicularis, n = 85; Macaca mulatta, n = 70; Papio hamadryas, n = 55; Colobus guereza, n = 76; Presbytis melalophos, n = 82; Presbytis rubicunda, n = 76). Results show that the interconulus has a significantly higher frequency and degree of expression in Tribe Papionini and exhibits ordered metameric variation with greatest expression in the third molars. Given the rarity of the interconulus in other closely related taxa, and its morphological distinction from the purportedly homologous features in other primates, we interpret the high degree of expression of the interconulus to be a trait derived in papionins that originated in the Miocene baboon/macaque ancestor.