Bio: Olivier Langrand is an academic researcher from World Wide Fund for Nature. The author has contributed to research in topics: Lemur & Population. The author has an hindex of 6, co-authored 10 publications receiving 339 citations.
01 Jan 1993
TL;DR: The population dynamics of this species is reviewed in light of heavy predation pressure from two owls,particularly the implications of predation on social behavior and life-history traits of this small nocturnal primate.
Abstract: It has been postulated that predation has been an important selective force in molding social behavior in mammals. However, observations of predators taking primates are rare and most cases concern relatively large diurnal primates. For the lemurs of Madagascar little quantified information is available, and it has generally been assumed that predation by carnivores and raptors is rare. Contrary to expectations there is a considerable amount of data on the topic, derived from several different sources, which is presented herein. The most detailed information on lemur predation is for Microcebus murinus. The population dynamics of this species is reviewed in light of heavy predation pressure from two owls (Tyto alba and Asio madagascariensis),particularly the implications of predation on social behavior and life-history traits of this small nocturnal primate.
TL;DR: The ring-tailed lemur Lemur catta is generally considered to be a species of dry deciduous forest, gallery forest and spiny thorn scrub at relatively low altitudes.
Abstract: The ring-tailed lemur Lemur catta is generally considered to be a species of dry deciduous forest, gallery forest and spiny thorn scrub at relatively low altitudes. During a survey of the summit zone of the Andringitra Massif, one of the most climatically extreme areas on Madagascar, we recorded this species above the tree-line at 2520 m in an area composed mostly of exposed rock, low ericoid bush and subalpine vegetation. Information was collected on food plants consumed by this species. This pelage coloration of the local population of L. catta differed from museum specimens and photographs taken from other areas of this species's range. The taxonomic status of the Andringitra population is in need of further study.
TL;DR: Regurgitated food remains of the Barn Owl Tyro alba were collected within the rain forest of the Eastern Region of Madagascar and in the sub-arid thorn scrub of the Western Region (Beza Mahafaly).
Abstract: Summary Goodman, S. M., Langrand, O. & Raxworthy, C. J. 1993. The food habits of the Barn Owl Tyro alba at three sites on Madagascar. Ostrich 64:160-171. Regurgitated food remains of the Barn Owl Tyro alba were collected within the rain forest of the Eastern Region of Madagascar (Andasibe and Manombo) and in the sub-arid thorn scrub of the Western Region (Beza Mahafaly). The material from Andasibe and Manombo represent sine point samples, while 24 samples were collected from Beza Mahafaly between November 1990 and November 1991. A minimum or 176 individual vertebrates, representing 18 taxa, was identified from the Andasibe sample, and a minimum of 90 individual vertebrates of 5 taxa from the Manombo sample. The Beza Mahafaly samples included a minimum of 1013 individual vertebrates of 22 taxa. At all three sites introduced rodents made up the bulk of the prey by number and by biomass, but at Beza Mahafaly lemurs and amphibia were also significant prey items. Insects constituted a small proportion of the p...
TL;DR: Food remains recovered from regurgitated pellets of the Madagascar Long-eared Owl Asio madagascariensis were collected at two sites on Madagascar with different habitats and weather regimes.
Abstract: Summary Goodman, S M, Langrand, O & Raxworthy, C J 1993 Food habits of the Madagascar Long-eared Owl Asio madagascariensis in two habitats in southern Madagascar Ostrich 64:79-85 Food remains recovered from regurgitated pellets of the Madagascar Long-eared Owl Asio madagascariensis were collected at two sites on Madagascar with different habitats and weather regimes The localities are Beza Mahafaly, a sub-arid thorn scrub area in the southwest, and Bezavona Forest, a lower montane rain forest in southeastern Madagascar At Beza Mahafaly prey composition varied according to season Vertebrate prey included: frogs, lizards, birds, terrestrial insectivores, bats, lemurs and rodents The total biomass of lemurs (Microcebus) represented varies from approximately 8 to 40% Two samples from the Bezavona Forest included: frogs, geckos, birds, bats, lemurs and rodents Lemurs (Microcebus and either Hapalemur or Avahi) made up a total biomass of 24 % at this locality At both sites a significant proportion
TL;DR: Les Cryptoproctes rencontres dans cette region d'environnement extreme se nourrissent d'une grande variete de Vertebres qui presentent des masses comprises entre 7 g and 544 g as discussed by the authors.
Abstract: Les informations presentees, relatives au regime alimentaire de Cryptoprocta ferox dans la zone sommitale (1 950-2 600 m) du massif d'Andringitra a Madagascar, sont basees sur l'analyse des feces. Les Cryptoproctes rencontres dans cette region d'environnement extreme se nourrissent d'une grande variete de Vertebres qui presentent des masses comprises entre 7 g et 544 g. La consommation d'insectes et de crabes a egalement ete mise en evidence. La masse moyenne des proies consommees dans ce site est considerablement inferieure a celle trouvee dans d'autres regions de l'ile, ce qui est vraisemblablement lie a la structure generale de la communaute locale des Vertebres.
TL;DR: The role of primate socio-ecology is examined and it is concluded that primates are not prominently represented because the main questions asked in behavioral ecology are often irrelevant for primate behavior.
Abstract: We review evolutionary processes and mechanisms that gave rise to the diversity of primate social systems. We define social organization, social structure and mating system as distinct components of a social system. For each component, we summarize levels and patterns of variation among primates and discuss evolutionary determinants of this variation. We conclude that conclusive explanations for a solitary life and pair-living are still lacking. We then focus on interactions among the 3 components in order to identify main targets of selection and potential constraints for social evolution. Social organization and mating system are more closely linked to each other than either one is to social structure. Further, we conclude that it is important to seek a priori measures for the effects of presumed selective factors and that the genetic contribution to social systems is still poorly examined. Finally, we examine the role of primate socio-ecology in current evolutionary biology and conclude that primates are not prominently represented because the main questions asked in behavioral ecology are often irrelevant for primate behavior. For the future, we see a rapprochement of these areas as the role of disease and life-history theory are integrated more fully into primate socio-ecology.
TL;DR: A more comprehensive energy frugality hypothesis (EFH) is proposed, which postulates that the majority of lemur traits are either adaptations to conserve energy or to maximize use of scarce resources.
Abstract: The last decade's lemur research includes successes in discovering new living and extinct species and learning about the distribution, biogeography, physiology, behavior, and ecology of previously little-studied species. In addition, in both the dry forest and rain forest, long-term studies of lemur demography, life history, and reproduction, have been completed in conjunction with data on tree productivity, phenology, and climate. Lemurs contrast with anthropoids in several behavioral features, including female dominance, targeted female-female aggression, lack of sexual dimorphism regardless of mating system, sperm competition coupled with male-male aggression, high infant mortality, cathemerality, and strict seasonal breeding. Hypotheses to explain these traits include the "energy conservation hypothesis" (ECH) suggesting that harsh and unpredictable climate factors on the island of Madagascar have affected the evolution of female dominance, and the "evolutionary disequilibrium hypotheses" (EVDH) suggesting that the recent megafauna extinctions have influenced lemurs to become diurnal. These hypotheses are compared and contrasted in light of recent empirical data on climate, subfossils, and lemur behavior. New data on life histories of the rain forest lemurs at Ranomafana National Park give further support to the ECH. Birth seasons are synchronized within each species, but there is a 6-month distribution of births among species. Gestation and lactation lengths vary among sympatric lemurs, but all lemur species in the rain forest wean in synchrony at the season most likely to have abundant resources. Across-species weaning synchrony seen in Ranomafana corroborates data from the dry forest that late lactation and weaning is the life history event that is the primary focus of the annual schedule. Lemur adaptations may assure maximum offspring survival in this environment with an unpredictable food supply and heavy predation. In conclusion, a more comprehensive energy frugality hypothesis (EFH) is proposed, which postulates that the majority of lemur traits are either adaptations to conserve energy (e.g., low basal metabolic rate (BMR), torpor, sperm competition, small group size, seasonal breeding) or to maximize use of scarce resources (e.g., cathemerality, territoriality, female dominance, fibrous diet, weaning synchrony). Among primates, the isolated adaptive radiation of lemurs on Madagascar may have been uniquely characterized by selection toward efficiency to cope with the harsh and unpredictable island environment.
TL;DR: Systematic direct evidence of the effects of predation can best be obtained by studying predators that are as habituated to observers as are their primate prey, and on systematically obtained indirect evidence is relied on.
Abstract: It has long been thought that predation has had important ecological and evolutionary effects on primates as prey. Predation has been theorized to have been a major selective force in the evolution of hominids.1 In modern primates, behaviors such as active defense, concealment, vigilance, flight, and alarm calls have been attributed to the selective pressures of predation, as has group living itself. It is clear that primates, like other animals, have evolved ways to minimize their risk of predation. However, the extent to which they have been able to do so, given other constraints of living such as their own need to acquire food, has not yet been resolved. Perhaps most hotly debated is whether predation has been the primary selective force favoring the evolution of group living in primates. Part of the difficulty in resolving the debate lies in a paucity of direct evidence of predation. This is regrettable yet understandable since primatologists, by definition, focus on the study of primates, not predators of primates (unless these are also primates). Systematic direct evidence of the effects of predation can best be obtained by studying predators that are as habituated to observers as are their primate prey. Until this is done, we must continue to rely on opportunistic accounts of predation and predation attempts, and on systematically obtained indirect evidence. Such data reveal several interesting patterns: (1) although smaller primates may have greater predation rates than larger primates, even the largest primates are not invulnerable to predation; (2) the use by primates of unfamiliar areas can result in higher predation rates, which might be one pressure favoring philopatry, or site fidelity; (3) arboreal primates are at greater risk of predation when they are more exposed (at forest edges and tops of canopies) than in more concealed locations; (4) predation by mammalian carnivores may often be episodic; and (5) terrestrial primates may not experience greater predation than arboreal primates.
TL;DR: It is shown that the diverse ecoregions of Madagascar share one distinctive climatic feature: unpredictable intra- or interannual precipitation compared with other regions with comparable rainfall.
Abstract: We show that the diverse ecoregions of Madagascar share one distinctive climatic feature: unpredictable intra- or interannual precipitation compared with other regions with comparable rainfall. Climatic unpredictability is associated with unpredictable patterns of fruiting and flowering. It is argued that these features have shaped the evolution of distinctive characteristics in the mammalian fauna of the island. Endemic Herpestidae and Tenrecidae and members of five endemic primate families differ from closely related species elsewhere, exhibiting extremes of “fastness” and “slowness” in their life histories. Climatic features may also account for the dearth of frugivorous birds and mammals in Madagascar, and for the evolutionary prevalence of species with large body mass.
TL;DR: A fundamental link between primate life history and social behaviour is demonstrated, the most basic type of variation in primate social organization is explained, and an additional determinant of social organization that may also operate in other mammals is proposed.
Abstract: Year-round association between adult males and females is common in primates, even though internal gestation and lactation predispose males to mate-desertion in the majority of mammals. Because there is little a priori support for alternative explanations, we hypothesized that permanent male-female association in primates serves to reduce the risk of infanticide by strange males whenever females and infants are closely associated. For a phylogenetic test of this hypothesis, we reconstructed the evolution of male-female and female-infant association among primates. The results of Maddison's concentrated changes test confirmed the prediction that mother-infant association, as opposed to infant parking, and female-male association did not evolve independently. Changes in litter size and activity, in contrast, were not significantly associated with evolutionary changes in male-female association. Thus, we demonstrate a fundamental link between primate life history and social behaviour, explain the most basic type of variation in primate social organization, and propose an additional determinant of social organization that may also operate in other mammals.