Infanticide in gelada baboons (Theropithecus gelada)

In a captive group of geladas three cases of infanticide have been observed after replacement of the harem-leader. Two of the infants were born before the replacement, the third one 12 weeks afterwards. The possible function of infanticide is discussed. Female counterstrategies other than avoiding contact with the male were not observed.     

The integration of an adult female gelada baboon (Theropithecus gelada)

An adult female gelada baboon has been integrated into an old-established group in the zoo in Rheine, West Germany. The integration took place in three steps: sight-contact, hourly meetings with the group, continuous stay in the group. Both the agonistic and the social-positive behaviour have been observed between the new female and the group-members. The integration was very difficult and lasted more than six months. The female was not really accepted, before she had not presented to the most dominant female of the one-male unit she has joined. This presenting only took place during the last part of the observations. In contrast to the adult female, the integration of juveniles occurred very quickly and nearly without any problems.     

Patterns of reconciliation among captive gelada baboons (Theropithecus gelada): A brief report

Animals that live in groups are frequently exposed to conflict situations and must in some way maintain group cohesion. One mechanism that appears to restore social relationships after they have been disrupted by conflict isreconciliation. This study investigated reconciliatory behavior in the gelada baboon,Theropithecus gelada. The subjects were 11 adult geladas, housed in a large outdoor enclosure at the Bronx Zoo/Wildlife Conservation Park, New York. Five-minute focal animal samples following spontaneous aggression were compared with 5-min matched-control samples. The results of this study were: (1) geladas reunited in a friendly way after aggression; (2) former opponents were attracted to one another rather than dispersed from one another after a conflict; (3) most post-conflict reunions occurred within the first 2 min of the post-conflict period; and (4) geladas do not have any specific types of behavior associated with post-conflict reunions as do chimpanzees and macaques. The results of this study support the hypothesis that gelada baboons reconcile after aggression.     

Vocalizations of adult gelada baboons (Theropithecus gelada): acoustic structure and behavioural context

Vocalizations and accompanying behaviors of adult gelada baboons were studied in four one-male groups kept in large outdoor enclosures in the zoos of Stuttgart and Rheine. Twenty-two acoustically different vocal patterns were determined. According to behavioural context, they were grouped into two categories: (1) contact calls and (2) aggressive and defensive calls. Frequency of calling and the production of different vocalizations were related to social rank and to the age of the sender. Vocalizations in species of the closely related genera Papio and Macaca are compared and their evolution is discussed.     

Derived vocalizations of geladas (Theropithecus gelada) and the evolution of vocal complexity in primates

Primates are intensely social and exhibit extreme variation in social structure, making them particularly well suited for uncovering evolutionary connections between sociality and vocal complexity. Although comparative studies find a correlation between social and vocal complexity, the function of large vocal repertoires in more complex societies remains unclear. We compared the vocal complexity found in primates to both mammals in general and human language in particular and found that non-human primates are not unusual in the complexity of their vocal repertoires. To better understand the function of vocal complexity within primates, we compared two closely related primates (chacma baboons and geladas) that differ in their ecology and social structures. A key difference is that gelada males form long-term bonds with the 2-12 females in their harem-like reproductive unit, while chacma males primarily form temporary consortships with females. We identified homologous and non-homologous calls and related the use of the derived non-homologous calls to specific social situations. We found that the socially complex (but ecologically simple) geladas have larger vocal repertoires. Derived vocalizations of geladas were primarily used by leader males in affiliative interactions with 'their' females. The derived calls were frequently used following fights within the unit suggesting that maintaining cross-sex bonds within a reproductive unit contributed to this instance of evolved vocal complexity. Thus, our comparison highlights the utility of using closely related species to better understand the function of vocal complexity.     

On hybridization between Theropithecus gelada and Papio anubis in the wild

Evidence is presented which suggests that Theropithecus gelada and Papio anubis may interbreed in the wild. The behavioural and ecological circumstances which give rise to this are discussed. The implications of these observations to the taxonomic status of these genera are assessed.     

Chest Color and Social Status in Male Geladas (<Emphasis Type="Italic">Theropithecus gelada</Emphasis>)

Conspicuous colored patches on animals often serve as sexually selected signals that advertise male quality. Such colored traits facilitate assessment of risks associated with a specific contest or benefits associated with a specific mate choice. Here, we investigate whether a colored patch of skin on the chests of male geladas (Theropithecus gelada) is a sexually selected signal. Specifically, we examine the relationship between color (redness), social status (a proxy for reproductive success), and age. We use observational data from known individuals from a population of wild geladas living in Ethiopia. We digitally quantified chest color using a previously-validated method for measuring color under field conditions. Results from this study are consistent with the hypothesis that redness is a quality signal in males. Baseline color correlates with status even when controlling for age. Indeed, males with redder chests were members of “better” groups: 1) leader males—the only males with reproductive access to females—had the reddest chests, and 2) within leader males, males with large units (>6 females) had redder chests than males with small units. At present, we are unable to address whether male chest color is directed at potential rivals or mates. Nevertheless, our data support the hypothesis that quality signals should prevail in large, fluid groups, where it is unlikely that individuals recognize all other group members. If individual recognition is limited in gelada society, this would favor the evolution of alternative means of assessment for making reproductive decisions.     

Blood groups of apes and monkeys. VII. The human-type A-B-H factors in gelada monkeys (Therapithecus gelada)

A series of 21 gelada monkeys (Theropithecus gelada) all showed strong reactivity of their saliva for H substance, but no reactivity for either A or B. Tests on their sera in no case showed the simultaneous presence of both the agglutinins anti-A and anti-B; instead some animals had only anti-A, others had only anti-B, while the remainder had neither anti-A nor anti-B. These findings distinguish gelada monkeys from all other species of Old World monkeys tested to date. They also provide further evidence supporting the genetic independence of the H substance and the A-B-O blood groups.     

Graminivory and Fallback Foods: Annual Diet Profile of Geladas (<Emphasis Type="Italic">Theropithecus gelada</Emphasis>) Living in the Simien Mountains National Park,Ethiopia

All primates show some dietary flexibility, particularly during food shortages. Foods consumed during times of scarcity (i.e., fallback foods) strongly influence the ecology and evolution of a species. Geladas (Theropithecus gelada) eat primarily graminoid leaves (i.e., grasses and sedges), but also consume other diet items (e.g., underground storage organs), especially in the dry season. We investigated the feeding ecology of wild geladas in the Sankaber region of the Simien Mountains National Park, Ethiopia across 12 mo. We asked how the gelada diet in this region, which is disturbed by livestock and agriculture, correlated with food availability and whether underground foods are fallback foods. We quantified the monthly diets of adults from eight reproductive units using instantaneous scan sampling, and seasonal aboveground and underground food availability using point-intercept transects and soil core sampling. Geladas primarily consumed graminoid leaves year-round (76.3% of the annual diet, 36.2–93.2% of the monthly diet) but spent considerable time consuming underground foods in the dry season (14.0% of the annual diet, 11.1–49.7% of the diet across dry season months). Graminoid consumption increased with graminoid availability, and underground food consumption decreased with graminoid availability. Underground food availability did not vary significantly between the dry and wet season sampling months, supporting the hypothesis that underground foods are fallback foods for geladas. We then compiled data from gelada feeding studies and found that underground foods are an important dry season diet item across study sites, but geladas rely more heavily on underground foods in habitats more heavily influenced by humans. Understanding the range and effects of primate dietary flexibility in human-modified habitats will contribute to a better understanding of how changing environments shape primate ecology and evolution.     

Fibrinopeptides A and B of baboons (Papio anubis, Papio hamadryas, and Theropithecus gelada): their amino acid sequences and evolutionary rates and a molecular phylogeny for the baboons

Amino acid sequences of fibrinopeptides A and B from savanna baboons, Papio anubis and Papio hamadryas, and highland baboon, Theropithecus gelada, were established. The sequences of the fibrinopeptides A from the three baboons were identical: (sequence: see text) The fibrinopeptides B were composed of 9 residues and demonstrated the sequence: (sequence see text) where X3 = Arg in P. anubis, His in P. hamadryas, and Gly in Th. gelada. Position-3 of the B peptides was the only replacement site observed among the 25 amino acid residues in both fibrinopeptides from the baboons. Based on these sequences, a molecular phylogeny for the three species of baboons was deduced. The evolutionary rates of the peptides B of the baboons and macaques were also estimated. It was observed that the fibrinopeptides changed at an uneven rate during the evolution of old-world monkeys, i.e., baboons and macaques.     

Theropithecus and 'Out of Africa' dispersal in the Plio-Pleistocene

Theropithecus oswaldi was one of the most widely distributed Plio-Pleistocene primates, found in southern, East, and North Africa, as well as in Spain, India, and possibly Italy. Such a large geographic range for a single primate species is highly unusual. Here, the nature and timing of its dispersal is examined using the Stepping Out cellular automata model. A hypothetical dispersal of T. darti is also modelled to assess whether the late Pliocene might have been a more favorable period for Afro-Eurasian dispersal than the early Pleistocene. Stepping Out draws on climatic and biome reconstruction to provide the paleovegetative and climatic background necessary for the simulations, and model parameters for T. oswaldi and T. darti were set a priori on the basis of their fossil records and paleobiologies. The simulations indicate that T. darti could have readily left Africa in the Pliocene, and that it swiftly reaches Asia. A European T. darti colonization was less certain and less rapid. The simulated T. oswaldi dispersal out of Africa was slower, but nonetheless T. oswaldi arrived at Mirzapur within the time period indicated by the fossil record. Using the a priori parameters, T. oswaldi did not arrive at the European sites of Cueva Victoria and Pirro Nord. It cannot be discounted, therefore, that some of the European fossils are a result of an earlier T. darti dispersal. The simulations also showed that in order for Theropithecus to reach Europe, it needed to be tolerant of a relatively wide range of habitats. In addition, our finding that Asian colonization was more rapid and more probable parallels the information from the hominin fossil record, in which the fossils from Asia predate those from Europe by several hundred thousand years.     

A model of the gelada socio-ecological system

Data from three populations of gelada baboons are used to generate a model of the species' socio-ecology that relates time budget requirements to group size, day journey length, and relevant environmental parameters. The model is used to examine the range of environmental conditions under which gelada could survive. This analysis indicates that a grazing primate like the gelada would run out of available time for foraging at just above and just below the altitudes at which they are now found. This suggests that, contrary to previous supposition, gelada were not driven into a retreat habitat by more competitivePapio baboons, but rather withdrew from lower altitude habitats because they could not survive under these conditions as the climate deteriorated during the Holocene.     

Play and social dynamics in a captive herd of gelada baboons (Theropithecus gelada)

Here, we provide quantitative data concerning adult and immature play distribution in geladas discussing the results in the light of their social dynamics. Sex differences in immature play does not seem to reflect sex differences in adult role; in fact, frequency, modality (C-play and LR-play), and motivation (measured by play initiations) to play did not vary according to the different sex-class combinations. The occurrence of adult-adult play suggests that geladas are characterized by an apparent more than actual rigidity in their social relationships and this is particularly evident in females which show peculiar traits in the use of social play. Specifically, adult females played with other adult females as much as with immature ones, thus suggesting their high motivation to engage in such interactions. This adult play behavioural pattern is typical of species showing relaxed/fluid more than despotic/rigid social relationships. Such assumption is also supported by the positive correlation observed between play and affinitive behaviours (grooming and agonistic support) found within each age-category (adult females and immature subjects). This evidence, together with the lack of correlation between aggressive contacts and social play, suggests that geladas use play for social assessment purposes and/or to increase their social affiliation levels.     

The reproductive cycle of the gelada baboon

Changes in the visual appearance of the sexual skins of female Theropithecus gelada associated with different stages of the reproductive cycle and with age are analysed using data from a large sample of females in the wild. Changes associated with the oestrous cycle and with pregnancy and birth are confirmed by a more detailed study of particular individuals. These signals are compared with those reported for other primate species. The behaviour of females during the course of the oestrous cycle is examined and compared with that reported for other species of Papio baboons.     

Periodic changes in the bare skin areas ofTheropithecus gelada

Daily examination of five adult female gelada baboons (Theropithecus gelada) exhibiting menstruation discharges showed noncyclic changes in the coloration of the bare areas of skin in throat, chest, and pubic areas. The intensity of red color in these areas were, on the other hand, markedly affected by the social context (bouts of threats or fights generally heighten the intensity of red) and by sickness or injury (generally lessening color intensity).The features showing most marked cyclic variations were color and degree of swellings of the cutaneous vesicles present around the chest and ventral patches, the intensity of both increasing in the middle of the menstrual cycle and descending as menstruation approaches, to gain intensity again a few days after cessation of the discharges. Of these two features vesicle color appears to be more sensitive to the hormonal changes underlying the variations.