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Morphometrics confirm taxonomic deflation in dwarf lemurs (Primates: Cheirogaleidae), as suggested by genetics
No full textFigure 2. Allometric and non-allometric craniodental characters in Cheirogaleus. (A) Palatal length (PALL), (B) temporal line (TpLi), and (C) second premolar height (P2), given in mm, are scaled against the greatest skull length (GSKL) for Cheirogaleus medius, Cheirogaleus adipicaudatus, Cheirogaleus major, Cheirogaleus ravus, Cheirogaleus sibreei, and unknown specimens, as assessed by Groves (2000).Published as part of Groeneveld, Linn F., Rasoloarison, Rodin M. & Kappeler, Peter M., 2011, Morphometrics confirm taxonomic deflation in dwarf lemurs (Primates: Cheirogaleidae), as suggested by genetics, pp. 229-244 in Zoological Journal of the Linnean Society 161 (1) on page 235, DOI: 10.1111/j.1096-3642.2010.00634.x, http://zenodo.org/record/575625
) in captivity
No full textFour pairs of captive crowned lemurs (Lemur coronatus) were studied during their annual breeding season in order to obtain baseline data on their reproductive biology for comparison with other Lemur species and to enhance their captive breeding success. Vaginal smears, testicular measurements, and records of the Duke University Primate Center provided the presented data. During a single breeding season, females cycled an average of three times, with an average cycle length of 34 days. Cycles were detected between November and March. Vaginal estrus and copulations were limited to one day per cycle. After 125 days of gestation females gave birth to one or two young. Both sexes attained sexual maturity at an age of about 20 months. Mean male testis size peaked in late December; at the same time, three of the females experienced their first estrus. Based on all available data, there was a significant positive correlation between cycle length and gestation length in the genus Lemur
Lemur Origins: Rafting by Groups of Hibernators?
No full textWhen and how non-human primates first arrived on Madagascar remains one of the most enigmatic questions in primate evolution [1-3]. Madagascar broke away from the African mainland and India long before the estimated origin of the first primates [4-7]. Because African and Asian lorises are the closest living relatives of Malagasy primates, however, some of their common ancestors must have migrated to distant islands or continents. Recent phylogenetic analyses strongly indicate an African origin for lemurs and lorises, thereby supporting a primate colonisation of Madagascar from Africa [8], but proposed mechanisms for this transoceanic colonisation have been highly controversial. Here I cite evidence from several recent studies that suggest a likely mechanism for a successful colonisation across the formidable water barrier of the Mozambique Channel
The evolution of childhood as a by-product?
No full textThe proposition that selective advantages of linguistic skills have contributed to shifts in ontogenetic landmarks of human life histories in early Homo sapiens is weakened by neglecting alternative mechanisms of life history evolution. Moreover, arguments about biological continuity through sweeping comparisons with nonhuman primates do not support various assumptions of this scenario
Patterns of Sexual Dimorphism in Body Weight among Prosimian Primates
No full textMany primatologists believe that there is no sexual dimorphism in body size in prosimian primates. Because this belief is based upon data that came from only a few species and were largely flawed in some aspect of sample quality, I re-examined the extent of sexual dimorphism in body weight, using weights of 791 adult prosimians from 34 taxa recorded over the last 17 years at the Duke University Primate Center. There was no significant sex difference in body weight in 17 species, but males were significantly larger in Nycticebus pygmaeus, Tarsius syrichta, Galago moholi, Galagoides demidovii, Otolemur crassicaudatus and Otolemur garnettii. Moreover, females were significantly larger in Microcebus murinus. Thus, the general lack of sexual dimorphism could be confirmed, notably for lemurs, but prosimians as a group show more variability in sexual size dimorphism than was previously thought. After including previously published data obtained in the wild from 8 additional species, I found significant heterogeneity in the degree of sexual dimorphism at the family level, but only the Indridae and Galagidae were significantly different from each other. Among the prosimian infraorders, the Lorisiformes were significantly more dimorphic than the Lemuriformes. Differences in dimorphism between higher taxonomic groups are discussed in the context of prosimian evolution, concluding that phylogenetic inertia cannot provide a causal explanation for the evolution of sexual dimorphism. The relative monomorphism of most prosimians may be related to allometric constraints and, especially in the Lemuriformes, to selective forces affecting male and female behavioral strategies
Reconciliation and post-conflict behaviour in ringtailed lemurs, Lemur catta and redfronted lemurs, Eulemur fulvus rufus
No full textThe post-conflict behaviour of two species of prosimian primates was recorded to examine the effects of agonistic interactions on the subsequent behaviour of former opponents. A total of 125 dyadic agonistic interactions between adults of both species were randomly selected during observations of two social groups of each species. During the 10 min following each agonistic interaction (post-conflict), all social interactions of one of the opponents with all group members, including the former opponent, were recorded and compared with baseline rates established by matched-control observations. In ringtailed lemurs, L. catta, the probability of affinitive interactions between former opponents was not affected by a preceding conflict. In redfronted lemurs, E. fulvus rufus, rates of affinitive interactions between former opponents were significantly above baseline levels in the first 2 min following a conflict, and former opponents were selectively attracted to each other. These post-conflict reunions may function as reconciliations. Significantly larger proportions of undecided conflicts, low-intensity conflicts and conflicts between related redfronted lemurs were reconciled, and victims of aggression were significantly more likely to initiate reconciliation. Neither species showed evidence of consolation, i.e. significantly increased affinitive contact between victims of aggression and third parties during the post-conflict period. Ringtailed lemurs, which have a clear dominance hierarchy and within-group kinship structure, showed a trend toward an increased probability of renewed conflict with former opponents, but not with other group members, during the post-conflict period. They provide the first documented example of a highly social species that appears to lack behavioural mechanisms to cope with the dispersive effects of intra-group aggression. These results demonstrate that reconciliation is not limited to the relatively large-brained anthropoid primates, that reconciliation is not a necessary consequence of group life, and that the occurrence of reconciliation is not limited to species with formalized dominance relations
Determinants of primate social organization : Comparative Evidence and new insights from Malagasy Lemurs
No full textThe aim of this review is to summarize newly available information on lemur social systems, to contrast it with the social organization of other primates and to relate it to existing models of primate social evolution. Because of their evolutionary history, the primates of Madagascar constitute a natural experiment in social evolution. During millions of years of isolation, they converged with other primates only in the most fundamental way in the evolution of solitary, pair-living and group-living species, but deviate in several respects within these basic categories of social organization. Solitary lemurs remain poorly studied, but their social organization appears to be broadly similar to that of other solitary primates, even though the unexpected lack of sexual dimorphism may indicate that similar types of social organization can give rise to different mating systems. The determinants of a solitary lifestyle remain elusive. Pair-living lemurs show striking convergences with other monogamous primates in several behavioural traits, but also deviate in that the majority of species are at least partly nocturnal and do not exhibit direct paternal care of dependent young. Group-living lemurs have not evolved single-male groups, male-bonded and multi-level societies, and polyandrous groups may also be lacking. Female philopatry is common, but female bonds are generally weakly developed and eviction of females from natal groups is not unusual. Group-living lemurs also differ from anthropoids in that their groups have even adult sex ratios, smaller average size and may split up on a seasonal basis. Feeding competition, predation risk and reproductive competition can not fully explain these unusual aspects of lemur social organization. It has therefore been suggested that the social consequences of the risk of infanticide and of recent changes in activity may be ultimately responsible for these idiosyncracies of group-living lemurs, an explanation largely supported by the available evidence. Thus, social factors and fundamental life-history traits, in addition to ecological factors, contribute importantly to variation in social systems among lemurs, and possibly other primates. However, neither the diversity of lemur social systems, nor the evolutionary forces and mechanisms operating in these and other primates are yet fully understood
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