Showing papers in "International Journal of Primatology in 1982"

Correlates of sexual dimorphism in primates: Ecological and size variables

Abstract: The effects of a series of ecological and size factors on the degree of sexual dimorphism in body weight and canine size were studied among subsets of 70 primate species. Variation in body-weight dimorphism can be almost entirely attributed to body weight (83% of variance R2 of weight dimorphism). Much smaller amounts of the variation can be attributed to mating system (R2 =6.8%,polygynous species being more dimorphic than monogamous ones) and diet (R2 = 2.5%,frugivorous species being more dimorphic than folivorous ones). Habitat (arboreal vs. terrestrial) and activity rhythm (nocturnal vs. diurnal) have only an indirect effect on weight dimorphism. Variation in canine-size dimorphism can be explained in terms of canine size (R2 =49%),activity rhythm (R2 = 20%,diurnal species being more dimorphic than nocturnal ones), and mating system (R2 = 10%).Habitat and diet do not play a significant role in canine-size dimorphism. The unexpectedly high contribution of size to sexual dimorphism coupled with the observation of increased sexual dimorphism with increased size leads us to formulate a new selection model for the evolution of sexual dimorphism. We suggest that if there is selection for size increase, whatever its cause, directional selection in both males and females will lead to an increase in sexual dimorphism based on differences in genetic variance between the sexes. Sexual selection, resource division between the sexes, or lopsided reproductive selection need not play a role in such a model.

Agonistic dominance in male baboons: An alternative view

Abstract: Data on baboons have generated both the concepts normally associated with male dominance hierarchies among primates and the tests of their significance. The priority-of-access model has been used to predict the relationship between dominance rank and resource acquisition. While the correlation between these two factors, or between rank and measures of reproductive success, has varied among different primate species, most recent baboon field-workers have interpreted their results to be consistent with the model. Based on 1200 hr of observation of a troop of savannah baboons near Gilgil, Kenya, this paper presents data on male agonistic interactions and on male acquisition of resources. Predictions of the priority-of-access model are tested and an inverse relationship is found between agonistic dominance rank and acquisition of two limited resources, estrous females and meat. The importance of the residency status of males is explored and an alternative hypothesis is presented to account for the anomalous pattern in the data. The relationship of male reproductive success and dominance rank is evaluated in light of the data on these baboons and the “residency” hypothesis.

Catalogue of primates in the British Museum (natural history) and elsewhere in the British isles. Part II: Family cercopithecidae, subfamily cercopithecinae

Abstract: The British Museum (Natural History) [BM(NH)], London, collection of modern primate specimens is among the most extensive and complete in the world, of major importance for studies of taxonomy, ecology and distribution, morphology, and phylogeny. The availability of a published catalog of this collection is of great value, especially given the amount of detail provided by this comprehensive work. As with her earlier (1976) catalog of the BM(NH) platyrrhine holdings, Mrs. Napier not only has listed the available specimens of Cercopithecinae, but also has engaged in some summary revision at the species and subspecies levels in order to assure herself (and thus the reader) of correct identifications. In addition to the BM(NH) zoological and osteological collections, the original fossils (and casts) in the museum's Subdepartment of Anthropology are included, as are specimens in most other British institutions (especially the Powell-Cotton Museum and the Odontology Collection of the Royal College of Surgeons). An introduction to the format and methods leads into the catalog itself, which begins with a short review of Old World monkey evolution by Peter Andrews. Five appendixes present mainly selected measurements and anatomical data on cercopithecines, drawn from the literature and original observations. These are followed by a complete bibliography and index to cited taxa. For each cercopithecine genus, the catalog provides a short discussion of synonymy, taxonomic notes, morphology, range, ecology, social behavior, reproduction, and species recognized. In turn, species' specimen lists are preceded by synonymy, type localities (of synonyms), taxonomic notes, ranges, keys to subspecies when relevant, and data on body lengths and weights also tabulated in Appendix II (and V). Individual specimens are listed by subspecies and country (or region) of origin, with the locality data as detailed as possible. The listing also includes the date of collection; the sex, age, and nature of the specimen;

Behavioral ecology of Alouatta seniculus in Andean cloud forest

Abstract: The behavior and ecology ofAlouatta palliate are well studied; we report here on the first long-term study of anotherAlouatta species, the red howler monkey,A. seniculus. AlthoughA. seniculus was studied at a high elevation in the Colombian Andes, it exhibits many behavioral and ecological similarities to lowlandA. palliata. Continuous focal sampling indicates thatA. seniculus spends 78.5% of its time resting, 5.6% moving, and 12.7% feeding. It has a day range of 1.09 km and a home range of 22 ha. Like its more northern relative,A. seniculus spends more than 50% of its feeding time on leaves–especially young leaves–but on a dry-weight basis, fruits comprise the majority of its diet. The small home and day ranges observed as well as the large amounts of time spent resting are all argued to be aspects of a relatively folivorous foraging strategy. Daily food intake is estimated to be 1.23 kg fresh weight (0.266 kg dry weight). Foraging efficiency (yield/time) varies by a factor of almost 6 across major food types, with item size and distribution being the key determinants. Food preferences change markedly over the activity period, with high-energy sources predominating early and high-protein sources late.

Patterns and determinants of monkey densities in Peru and Bolivia, with notes on distributions

Abstract: A comparative study of species assemblages and population densities was conducted on Amazonian monkey communities in 16 areas, ranging from 3°S latitude in northern Peru to 18°S latitude in southern Bolivia. The habitats ranged from several types of tropical rain forest in the more northern latitudes to dry, deciduous forest in the southernmost study area. The monkey populations of three of the study areas have historically received light hunting pressure; the rest have been moderately to heavily hunted. A transect census technique was used to estimate the relative and absolute densities of all diurnal monkey species except Cebuella pygmaea. The number of coexisting monkey species ranged from 4–6 in the southern areas to 12–14 in the northern areas. The reduction in species richness in central and southern areas of Bolivia is probably attributable to several inimical habitat factors. Predation by humans was found to be the single most important factor affecting monkey densities. Monkey densities, and especially biomasses, were much lower in areas not protected from hunting than in protected areas. Hunting did not affect all species equally. Larger-sized species are hunted more and have severely reduced numbers in unprotected areas, whereas the densities of smaller species are not noticeably diminished in unprotected areas. Large, herbivorous monkey species contributed the major proportion of the total monkey biomass in protected areas. The strong influence of hunting has largely obscured the effects of other factors on population densities.

Effects of inbreeding on infant mortality in captive primates

Abstract: Breeding records for 16 primate colonies representing six families and both suborders were obtained from 10 institutions breeding primates in captivity and from the international studbook on one endangered species. Inbreeding coefficients relative to the founding population were calculated for each individual born. Individuals with an inbreeding coefficient of zero were classified as “noninbred” those with inbreeding coefficients greater than zero, as “inbred.” Infant mortality was defined as all deaths prior to the age of 6 months. Infant mortality of inbred young was higher than that of noninbred young in 15 of the 16 colonies surveyed (P =0.0003, one-tailed sign test). The higher mortality rate of the inbred young was significant by a Fisher’s exact test with a probability less than or equal to 0.05 in five of the individual colonies: Lemur fulvus, Saguinus fuscicollis illigeri, Saguinus fuscicollis, Leontopithecus rosalia,and Mandrillus sphinx.

Wide-Ranging Chimpanzees at Mt. Assirik, Senegal

Abstract: A 4-year study of the ecology and ethology of wild chimpanzees (Pan troglodytes verus)was carried out in far western Africa. Contacts with chimpanzees and the locations of their nests were noted to determine which types of habitat were most used and to estimate the density of the population and the size of its home range. The results show that this community has one of the lowest densities and largest home ranges of all populations of chimpanzees studied so far. As such, it may provide a useful model for the reconstruction of hominid evolution in the Plio-Pleistocene.

Feeding behavior of yellow baboons (Papio cynocephalusin) the Amboseli National Park, Kenya

Abstract: The results of an 11-month field study of the feeding behavior of adult yellow baboons (Papio cynocephalus)are presented. Although catholic feeders, the baboons are not unselective in their choice of foods, and a small number of foods account for the bulk of their feeding time and are significant determinants of their home-range utilization patterns. These preferred foods are consumed throughout the year, a response, perhaps, to relatively minor fluctuations in their availability. Seasonal changes in food abundance are, however, reflected in other aspects of the baboons’ feeding behavior, including a tendency to show greater day- to- day dietary variability during periods of higher rainfall and greater overall food availability. It is suggested that this, and other, aspects of baboon feeding behavior can be understood only in the context of the extremely “patchy” distribution of their food supplies.

Sivapithecus simonsi, a new species of miocene hominoid, with comments on the phylogenetic status of the ramapithecinae

Abstract: The Ramapithecinae are an extinct, mainly Miocene group of hominoids, whose relationship to modern taxa is disputed. Some regard them as hominids, while others view them as ancestral toPongo,or even as the group ancestral to both hominids and extant apes. In this paper a systematic revision of Ramapithecinae is undertaken. Sivapithecus sivalensis andRamapithecus punjabicus are considered the same species, with the former name having priority. A new Indian species,Sivapithecus simonsi,is recognized. Ramapithecine anatomy is reviewed and compared with that of gracileAustralopithecus, early and middle MioceneProconsul andDryopithecus, and living pongidsPan, Gorilla, andPongo.Ramapithecines are shown to be much more primitive or “ape-like” than some have argued. Anatomical data are evaluated cladistically with several results. Parallel evolution in the jaws, teeth, and facial structure of hominoids appears to be the rule rather than the exception. Bearing this in mind, nevertheless, from the available evidence of anatomy, ramapithecines are cladistically hominids.

The ecology of singing in Kloss' gibbons (Hylobates klossii) on Siberut Island, Indonesia

Abstract: Data are presented from a study of habituated Kloss gibbons on Siberut Island, Indonesia. Male Kloss gibbons can sing at any time from 0100 to 1300 hr, but the majority of songs is concentrated in the hour before dawn. Female Kloss gibbons sing only after dawn and the song bout includes a dramatic visual display. Neither countersinging nor coordinated chorusing has been proved in either sex. Males sing before dawn as often as possible but are inhibited by wet nights and by minimum temperatures below 21.5°C; postdawn songs of both sexes are inhibited by rain. The occurrence of any particular type of song bout is independent of the occurrence of the other types. Song trees used by males and those used by females do not differ in height. Song trees emerged from the neighboring canopy more than other available trees of similar height in the gibbons’ home range. Female song trees were most abundant on the slopes and where the trees were tallest. Almost all the male’s night trees could have been used for singing from had the weather been suitable. There was a greater likelihood of the male’s traveling a long way to the day’s first fruit source on mornings when he sang before dawn than on mornings when he did not. Considerations of sound transmission through tropical rain forest reveal that the times and frequencies used for singing by Kloss gibbons are optimal for communicating with neighboring groups.

Preliminary observations of the Mentawai macaque on Siberut Island, Indonesia

Abstract: During 2 years spent conducting ecological fieldwork on Siberut, the largest and most northerly of the four Mentawai Islands in Indonesia, incidental observations were made of the Mentawai macaque. The Mentawai macaque has been considered variously as a full species similar in some respects to the long-tailed macaque and as a subspecies of the pig-tailed macaque. Evidence is presented that a hitherto undescribed form of the Mentawai macaque occurs on Siberut, and aspects of its ecology and behavior are described.

The influence of behavioral context and social characteristics on the physical aspects of social grooming in rhesus monkeys

Abstract: The extent to which dominance status and sex can influence the physical act of grooming was examined in two groups of rhesus monkeys. Both the sex and the dominance status of the groomee, but not of the groomer, were found to affect the body sites groomed and the positions assumed by the animals during the grooming bout. Females were groomed more on the back and head and less on the tail, rump, upper leg, and lower arm than males. Females with infants tended to face away from the groomer. Higher-ranking groomees were groomed more on the tail and rump and less on the upper leg and back than lower-ranking groomees. Higher-ranking groomees spent more time lying down during grooming than lower-ranking groomees, while lower-ranking groomees faced away from the groomer more then higher-ranking groomees. The behavioral interactions just prior to and immediately after grooming were also recorded. Although the onset of grooming was preceded by social interactions between the partners, the end of grooming was followed by a complete break in interactions. Particular types of social signals displayed by the groomee just prior to grooming were highly correlated with the grooming of specific body sites. These results suggest that the groomee controls the behavior of the groomer by the social signals it displays and the positions it maintains during the grooming bout. Thus, the grooming act itself may play an important role in the social relationships between group members.

Adult male replacement inMacaca fascicularis of East Kalimantan, Indonesia

Abstract: This report on wild-ranging crab-eating macaques in East Kalimantan, Indonesia, describes male replacements for the first time in this species. A replacement at the alpha rank by an immigrant adult male was seen in this multimale troop during each year of the 20-month field study. The data show considerable variation in the process and outcome of social change. Adult male immigrants contested the alpha rank, whereas subadult male immigrants did not. The first replacement took 2 days, whereas the second one took 1 month. In the first replacement four males and 10 other residents left the troop. In the second replacement one of the two adult males was successful in immigrating when he replaced the resident male of his alpha rank, but the deposed alpha male was not evicted from the troop. Existing models of the causes of replacement (such as high density or human disturbance) and of the causes of infanticide are not supported by these data. Infanticide by immigrating males was not observed despite the apparent presence of the postulated circumstances conducive to infanticide.

Beach troop of the Gombe

Abstract: Dr. Ransom's research on two of the baboon troops at the Gombe Reserve in Tanzania, made famous by Jane Goodall's work on chimpanzees, was carried out more than 10 years ago. The book is adequately updated by frequent references to the excellent studies completed at the Gombe after the author's stay there, and to studies carried out elsewhere as well. The presentation is less quantitative than many workers might find acceptable today, but that very fact makes it a pleasure to read, since it is well written and the explanations are very reasonable and clear. The author sets a valuable precedent with this study, which, combined with the research of more recent scientists at the Gombe, is the longest and most exhaustive investigation of \"savanna\" baboons to date, matched only by that of Hans Kummer and his students on hamadryas baboons. When the author began work, no studies had yet been completed in which all the individual animals were known, nor had the same team of researchers remained in the field for an uninterrupted period of as long as 18 months. Beach Troop of the Gombe is a valuable combination of a detailed report on the first study of baboons at Gombe and less detailed reports on later studies, for which references are given for those who wish to pursue them further. The fact that these savanna baboons actually live in a forest makes comparison with other populations even more interesting. The section dealing with chimpanzee predation on baboons is especially interesting because it presents the only analysis yet available from the baboons' rather than the chimpanzees' point of view. Much has been made of the chimpanzees' hunting techniques and ability, but only the book under review considers the baboons' evident failure to respond effectively to this attack. The section on sexual behavior is also particularly excellent, being very thorough, perceptive, and clear. Other sections describe and analyze demography, ecology, communication, social organization and troop structure, and intertroop relations. The author's theoretical points are 507

Hominid and gelada baboon evolution: Agreement between molecular and fossil time scales

Abstract: The time of origin of the hominid lineage has long been debated. Macromolecular studies have consistently shown genetic distances between living humans and African apes to be quite small. The molecular clock hypothesis proposes that the time of separation of these lineages is relatively recent (in the range of 4–8 million years ago) and not 15 million years or more ago as usually suggested. Three independent molecular comparisons yield a mean estimate of 4.6 million years for the hominid-African pongid divergence. The relationship of Theropithecusand Papiois a parallel case within Primates of two taxa which are quite similar at the molecular level, but which are usually thought to have separated relatively long ago. The two cases of seeming discordance between different lines of evidence are analogous. Each involves a speciation event which eventually resulted in one substantially derived lineage and one or more relatively unchanged lineages. In each case, claims of the antiquity of the divergence event extend to at least twice the age of the first certain appearance of the more derived lineage in the fossil record. Finally, in each case, the molecular clock model suggests a range of possible divergence times that overlaps with the first appearances of undoubted hominids and Theropithecusin the fossil record. This test involving paleontological evidence supports the molecular clock hypothesis.

Seasonal rank changes for adolescent and subadult natal males in a free-ranging group of rhesus monkeys

Abstract: Changes in dominance rank for adolescent and subadult natal males in a semi-free-ranging rhesus macaque group were seasonal. Three 4-year-old natal males of the highest-ranking matriline occupied high ranks in the adult male dominance hierarchy during the premating period. In the mating season they dropped in rank, and this decrement was related to a concomitant drop in their alliances. After the mating season, these males rose in rank along with their two 3-year-old kin to occupy ranks 2–5 and 7–8 in the adult male dominance hierarchy. Three-year-old natal males of matrilines lower ranking than first did not become integrated into the hierarchy at this time.

A test of the randomness of paternity of members of maternal sibships in six captive groups of rhesus monkeys (Macaca mulatta)

Abstract: Results of previous studies have shown that in captive groups of rhesus monkeys (Macaca mulatto)fathers associate more frequently with their own offspring than with those of other males and that mothers are most permissive of physical contact between their own infant and a juvenile when that juvenile shares the same father with her infant. These two observations suggest that the identity of offspring born in captive groups of rhesus monkeys is recognized by at least some adult members of the group. Consistent patterns of mating among mating seasons might explain this apparent recognition of offsprings’ paternity. Fathers, for example, might regularly associate with young who maintain a close relationship with females with whom they have previously mated, and mothers might selectively permit juveniles who maintain a close relationship with males with whom they have previously mated to associate with their infants. This hypothesis is tested in this paper by comparing the observed distribution of 70 maternal sibships, members of which were fathered by the same or by different adult males over a 4-year period in six captive groups of rhesus monkeys, with that distribution expected based on random mating from season to season. Seasonal mating patterns were found to be random. Preparations are now underway to test this hypothesis in several free-ranging groups.

Sexual behavior in aging male rhesus macaques: Effects of test duration on sexual performance

Abstract: The sexual behavior displayed by nine old (20-year and older) rhesus (Macaca mulatta) males in 10-min tests was compared to that displayed in 1-hr tests. The tests were part of a long-term study on the decline in male sexual activity that accompanies old age. The males were paired with 10 ovariectomized, estrogentreated females in two blocks of 10 tests; each male was tested once with each female in each test block. The percentages of males that achieved intromissions and ejaculated in the two test blocks were the same (P 0.05), there was a significant positive correlation of performance in 10-min tests with performance in 1-hr tests. Assuming a random distribution of contacting, mounting, intromission, and ejaculation throughout the hour, we would have predicted a significantly lower number of these behaviors in the first 10 min of the 1-hr tests than we actually observed. The mean percentages of 1-hr tests with contacting, mounting, intromission, and ejaculation was significantly lower than that of 10-min tests conducted with the same males 11 years earlier. Thus, the decline in sexual performance was not an artifact of the limited (10-min) test duration.

Evolutionary biology of the new world monkeys and continental drift

Abstract: Approximately 50 species of monkeys belonging to 16 genera inhabit the tropical forests of the New World today. The extensively documented fossil record of mammalian evolution in South America indicates that primates first appeared there about 35 million years ago, and that the current diversity of New World monkeys is the result of subsequent radiations. This volume is aimed at determining the phyletic and geographical origins of New World monkeys. As the editors and contributors repeatedly emphasize, the problem of New World monkey origins involves at least four questions. Two of these are phyletic: (I) Do the anthropoids of the New and Old Worlds form a monophyletic group (that is, one which had a last common ancestor that would be identified as an anthropoid, rather than a prosimian)? (2) Which group (or groups) of Eocene prosimians gave rise to the earliest anthropoids? The other two questions are geographical: (3) How did the ancestors of New World monkeys get to South America? (4) Where did they come from? Debate over the phyletic origin of platyrrhine monkeys goes back to the beginning of the present century, when Gidley, Gregory, and others struggled to decide which group of North American prosimians, the lemur-like adapids or the tarsier-like omomyids, gave rise to New World anthropoids. The geographical questions became hot issues only after the general acceptance of continental drift in the late 1960s. Once it had been established that the South Atlantic had been much narrower in the early Tertiary than it is now, the French paleontologists Rene Lavocat and Robert Hoffstetter proposed that the higher primates and hystricomorph rodents that appear suddenly in the South American Oligocene had rafted in from Africa, where similar primates and rodents are known from the Fayum deposits of roughly the same age. Lavocat and Hoffstetter argued that a North American origin was less probable, because it involved a longer sea journey, less favorable currents, and implausible amounts of parallel evolution from the more primitive prosimians and rodents found in the Eocene of North America. Their arguments were generally rejected by other paleontol-

Endocrinology of pregnancy in the orang-utan (Pongo pygmaeus) and its evolutionary significance

Abstract: Urinary concentrations of estrone, estradiol-17Β, estriol, pregnanediol-3α-glucuronide, and chorionic gonadotrophin (CG) were measured by radio-immunoassy through five pregnancies in four multiparous orang-utans. The excretion of all three estrogen metabolites increased substantially during pregnancy. Although estrone was the major metabolite during early pregnancy, estriol excretion increased considerably, to reach 10 times the concentration of estrone at term. Estradiol-17Β was of comparatively minor importance. Maximum CG excretion occurred during the first trimester and low but constant levels were present in urine throughout the remainder of pregnancy. An early peak of pregnanediol-3α-glucuronide excretion coincided with the CG peak and then rose steadily to reach a plateau 8 weeks prepartum which was maintained until term. Urinary excretion of all five hormones decreased rapidly immediately following parturition. These data suggest that the pattern of urinary steroid and CG excretion during pregnancy in the orang-utan closely resembles that in the other great apes and women.