Biomedical subjects

R W Sussman

Publications and source records attributed to R W Sussman.

12 recordsLinked to original sources

PubMed2005

Importance of cooperation and affiliation in the evolution of primate sociality.

The idea that competition and aggression are central to an understanding of the origins of group-living and sociality among human and nonhuman primates is the dominant theory in primatology today. Using this paradigm, researchers have focused their attention on competitive and aggressive behaviors, and have tended to overlook the importance of cooperative and affiliative behaviors. However, cooperative and affiliative behaviors are considerably more common than agonistic behaviors in all primate species. The current paradigm often fails to explain the context, function, and social tactics underlying affiliative and agonistic behavior. Here, we present data on a basic question of primate sociality: how much time do diurnal, group-living primates spend in social behavior, and how much of this time is affiliative and agonistic? These data are derived from a survey of 81 studies, including 28 genera and 60 species. We find that group-living prosimians, New World monkeys, Old World monkeys, and apes usually devote less than 10% of their activity budget to active social interactions. Further, rates of agonistic behaviors are extremely low, normally less than 1% of the activity budget. If the cost to the actors of affiliative behavior is low even if the rewards are low or extremely variable, we should expect affiliation and cooperation to be frequent. This is especially true under conditions in which individuals benefit from the collective environment of living in stable social groups.

Activity Cycles↗

PubMed2003

Demographic and life-history patterns in a population of ring-tailed lemurs (Lemur catta) at Beza Mahafaly Reserve, Madagascar: a 15-year perspective.

Over 15 field seasons (1987-2001), we collected census and life-history data on a population of individually identified ring-tailed lemurs at the Beza Mahafaly Reserve, Madagascar. No significant difference was found in population size over the study period, though a marked decline in the population occurred following a 2-year drought. The population rebounded rapidly after the immediate postdrought period. There was nearly a complete replacement of individuals over the study period. Average group size is 11.5 animals, and adult male to female sex ratio is 0.92. Most females reproduce annually, and the average fecundity rate is 84.3%. The greatest variability in fecundity is found among old females. We suggest that ring-tailed lemur females follow an "income breeding" strategy, i.e., females use maximum resources during reproduction rather than relying on fat stores, as do "capital breeders." Infant mortality to 1 year of age in a nondrought year is 52%, higher than infant mortality in small to medium-sized anthropoids. The oldest known female was 18 years old in 2001. We suggest that 18-20 years may represent the maximum life-span for wild ring-tailed lemurs. Because males regularly emigrate from the population, we have no data regarding male life-span; however, there is some indication that males do not survive as long as females. Group fission has occurred three times: twice from one parent group living in the driest area of the reserve, with the most dispersed food resources. We suggest that the reproductive strategy that has evolved in this species, wherein females reproduce early in life and annually until old age, is a response to the unusual climate and environmental conditions under which Lemur catta has evolved.

Animals↗

PubMed2002

Dental and general health in a population of wild ring-tailed lemurs: a life history approach.

Data are presented on dental and general health for seven groups of wild ring-tailed lemurs, Lemur catta, from the Beza Mahafaly Reserve, in southern Madagascar. As part of a study of population demography, adults were captured, collared, and tagged, and biometric measurements, dental casts, and analyses of dental and general health were made. Results indicate that patterns of dental health vary by individual, age, sex, and habitat. Prime adults show more dental attrition than young adults. Prime males living in more marginal habitats show greater mean attrition than those living in richer habitats. Dental damage, specifically to the toothcomb, indicates that mechanical stresses to this region may include the initial harvesting of foods, in addition to grooming. Males exhibit more evidence of past trauma, including scars and chipped teeth. These results indicate that environmental as well as social factors, such as female dominance, may lead to sex differences in health patterns among lemurs.

Age Factors↗

PubMed2001

Analysis of dentition of a living wild population of ring-tailed lemurs (Lemur catta) from Beza Mahafaly, Madagascar.

Detailed descriptions of the dentition of many strepsirhine primate taxa are rare, despite their importance in understanding primate evolutionary biology. While several researchers have provided detailed morphological descriptions of ring-tailed lemur dentition (e.g., Schwartz and Tattersall [1985] Am. Mus. Nat. Hist. Anthropol. Pap. 60:1-100; Tattersall and Schwartz [1991] Am. Mus. Nat. Hist. Anthropol. Pap. 69:2-18), there are few studies (e.g., Eaglen [1986] Am. J. Phys. Anthropol. 71:185-201) that present quantitative data on the dentition of this species. Furthermore, prior analyses were based on museum specimens from various populations and locations. We present here quantitative and morphological data on the dentition of a population of wild Lemur catta from Beza Mahafaly Special Reserve, Madagascar. Measurements were made on dental casts (n = 39) taken from living members of this L. catta population. Our analysis indicates that no significant (P > 0.05) sexual dimorphism exists for the 30 dental measurements collected. These data support the generalizations (e.g., Plavcan and van Schaik [1994] Evol. Anthropol. 2:208-214; Kappeler [1996] J. Evol. Biol. 9:43-65) that little sexual dimorphism in dentition exists among Malagasy strepsirhines. In addition, the overall patterns of metric variation in this sample compare favorably with patterns seen among other primates, e.g., premolar measurements varying more than molars (e.g., Gingerich [1974] J. Paleontol. 48:895-903). However, there is a degree of intraspecific morphological variation indicated, with one of the morphological traits discussed in other studies as being species-specific for L. catta (absence of P(4) metaconids) observed to vary between specimens. Because the patterns of variation seen in this sample are from a known breeding population, the data presented here provide an important reference for interpreting and understanding the fossil record.

Animals↗

PubMed1995

Mitochondrial DNA of the Mauritian macaques (Macaca fascicularis): an example of the founder effect.

Macaque monkeys (Macaca fascicularis) were introduced to the island of Mauritius approximately 400 years ago. This study compares the mitochondrial DNA of macaques on Mauritius with those from Indonesia and the Philippines. The goal is to measure the amount of evolutionary change that has occurred in this isolated population over 400 years, and to address questions regarding the origin of the Mauritian founders. Amplification of the control region of the mitochondrial genome via the polymerase chain reaction yielded an 1800 base pair DNA fragment which was surveyed for variation using restriction endonucleases. Fifty-two macaques were separated into 17 haplotypes by mapping the restriction sites. No haplotypes were shared among the three populations, and only two closely related haplotypes appeared in the Mauritian sample. Nucleotide variation in the mitochondrial DNA in the Mauritian sample was 10-fold less than the Indonesian and Filipino samples. In contrast, allozyme data estimates of genetic diversity on Mauritius are similar to populations from the ancestral range. The evidence of the more severe bottleneck as measured by mitochondrial data may be explained in part by almost exclusive male dispersal in this species, and may support models of founder events in which rapid population growth prevents substantial loss of nuclear variation. The mitochondrial evidence supports the morphologically and historically based hypothesis that the original founders came from Indonesia.

Animals↗

PubMed1984

The ecological role of the callitrichidae: a review.

The marmosets and tamarins fill a unique ecological role among the anthropoid primates, one that has not been fully recognized. Many misconceptions--that they are primitive, monogamous, territorial, and squirrellike--pervade the literature. These misconceptions are largely the result of misinterpreting laboratory studies which have not been confirmed with identified animals in natural habitats. Recent field studies, reviewed here, indicate that marmosets and tamarins have a highly derived ecological role, are not monogamous, feed largely on insects and plant exudates, and have uniquely specialized positional behavior involving clinging to vertical tree trunks in order to feed on exudates. Accompanying these behavioral traits are a number clawlike nails on all digits except the hallux, and a three-cusped upper molar morphology. These form a suite of characteristics unique among the living primates, many of which are related to their ecological role. We believe that the marmosets and tamarins are members of a guild of exudate feeders in which plant exudates are an important component of the diet. It is within this framework of a primate foraging guild that we can best understand many of their morphological and behavioral adaptations.

Animals↗

PubMed1984

Ecological distinctions between sympatric species of Saguinus and Sciurus.

Tamarins are small New World monkeys that have been described as "squirrellike." Squirrels, along with bats and birds, are the taxa most likely to utilize resources similar to those used by primates in the tropical forest canopy. In this paper we compare differences in ecology, diet, locomotion, and habitat utilization between sympatric populations of tamarins (Saguinus oedipus) and tree squirrels (Sciurus granatensis) in Panama. Data presented indicate that although there is some degree of resource overlap, patterns of habitat utilization differ significantly. Rather than being "squirrellike," the Panamanian tamarin exhibits a pattern of locomotor and feeding behavior consistent with that found in other arboreal primates.

Animals↗

PubMed1979

Correlates between locomotor anatomy and behavior in two sympatric of Lemur.

Sympatric populations of Lemur catta and Lemur fulvus show major differences in their occupation of canopy forest levels. Lemur catta is usually found in the lowest levels of the forest, and uses the ground for travel over 65% of the time. Lemur fulvus uses the upper levels of the canopy forest and is observed on the ground in less than 2% of all observations. Comparison of hindlimb musculoskeletal anatomy show statistically significant differences in the lengths of the long bones and the height of the talus. Differences also occur in ranges of tibio-talar and mid-talar joint mobility. The details of insertion of the biceps femoris muscle are distinct in the two species as is the relative mass of muscle associated with flexion of the pedal digits, and flexion of th tibio-talar joint. The metric and morphological differences in the hindlimb anatomy of Lemur catta and Lemur fulvus are consistent with differences in habitat and substrate utilization.

Adaptation, Biological↗

PubMed1979

Statistical methods for analyzing data on daily activity cycles of primates.

Many field studies on primates have recently been carried out in which quantitative data have been collected using instantaneous scan sampling techniques. However, data collected in this manner are difficult to analyze statistically because of the problem of independence of samples, and a number of investigators have analyzed such data incorrectly. In this paper, we evaluate such analyses and suggest alternative techniques that may be more appropriate. Examples are drawn from data on daily activity cycles of Lemur catta and Lemur fulvus.

Activity Cycles↗

PubMed1978

Dietary and dental variations in the genus Lemur, with comments concerning dietary-dental correlations among Malagasy primates.

Field studies of feeding in the lemur subspecies Lemur fulvus rufus and L. f. mayottensis have revealed that feeding patterns within a single species can be markedly different, both regionally and seasonally. Thus L. f. rufus is a dietary specialist (3 plant species accounting for 80-90% of feeding time), and is highly folivorous, especially during the dry season (90% of feeding time spent eating leaves during the dry season, and 53% during the wet season). On the other hand, L. f. mayottensis is more generalized dietarily (the parts of 12 plant species accounting for 90% of feeding time), and is primarily frugivorous (64% of feeding time spent eating fruit, with a monthly maximum during the wet season of 79%. In both these respects, L. f. mayottensis resembles L. catta are more closely thant it does L. f. rufus. When size differences are corrected for, Lemur fulvus rufus has significantly longer second lower molar shearing crests than does L. f. mayottensis. Other folivorous Malagasy strepsirhines also tend to have long shearing crests than frugivorous forms. Some data on cheirogaleines also suggest that the more insectivorous species have better developed molar crests than frugivorous species. Some apparent exceptions to this pattern are noted, especially for Lemur catta, which in certain functional respects dentally more closely resembles L. f. rufus than L. f. mayottensis. The problems of dietary classifications are discussed.

Animals↗

PubMed1978

Foraging patterns of nonhuman primates and the nature of food preferences in man.

1) There are a variety of foraging and dietary patterns among primates; different species have generally obligate food habits. 2) There are a number of convergent dietary patterns among primates that are not taxonomically dependent; closely related species may have very different food habits, while the diets of unrelated forms may be quite similar. 3) At least at a general level, relationships exist between dietary patterns and alimentary tract adaptations. Further comparative studies of the histology of the gut tract of primates in conjunction with detailed and quantitative studies of the food habits of natural populations are needed to determine if more precise dietary/digestive tract relationships exist. Studies of this type should lead to a better understanding of digestive physiology. However, whether we can ever determine the "natural diet" of man by such comparisons, of course, still remains an unanswered question.

Animals↗

PubMed1976

Cycles of activity, group composition, and diet of Lemur mongoz mongoz Linnaeus 1766 in Madagascar.

A preliminary study of the ecology and behavior of Lemur mongoz mongoz was carried out in the northwest of Madagascar. The animals were observed for approximately 250 h in July till August, 1973, and for 50 h in June, 1974. L.m.mongoz has been reported to be diurnal and to live in groups of 6-8 individuals. However, we found the animals to be nocturnal and that groups contained an adult male, an adult female and their offspring (groups numbering from 2 to 4 individuals). L.m.mongoz is thus the only species of the genus Lemur studied to date that is active exclusively at night and that lives in family groups. L.m.mongoz was also found to have a very specialized diet. During our study, it was observed to feed on only five species of plant and mainly on the nectar-producing parts (flowers and nectaries) of four of these species. It spent most of its feeding time licking nectar from the flowers of the kapok tree, Ceiba pentandra, and is probably a major pollinator of this tree in Madagascar. In Africa and South and Central America, the kapok tree is usually bat-pollinated. A dietary preference for nectar, although common among bats, has not previously been observed in primates.

Animals↗