Habitat separation of semifree-ranging Lemur catta and Lemur fulvus

Habitat use of two semifree-ranging groups of lemurs, Lemur catta and Lemur fulvus, was studied in relation to abiotic, floristic, and structural characteristics of their enclosure. L. catta was very flexible in the use of the habitat and showed a tendency for random utilization. But this species reacted quickly to changes of the abiotic environment. L. fulvus preferred to stay in areas with dense vegetation but good lateral visibility and close to the food plants. Abiotic factors such as solar radiation and ambient temperature influenced L. fulvus to a lesser extent than L. catta. According to these results L. catta could be considered to be adapted to variable environments where it is advantageous to react quickly to changes of abiotic factors. The conservative habitat use and the limited response to abiotic factors of L. fulvus might reflect adaptations of a species living in a stable environment. If these interpretations prove correct, then this study provides another example of animals born and raised in captivity that have retained habitat preferences of their wild conspecifics.     

Discrimination by male ring-tailed Lemurs (Lemur catta) between the scent marks of male and those of female conspecifics

Olfaction plays an important role in the social communication of all prosimians. (The experiment reported in this paper forms part of an intensive chemobehavioral study of olfaction in Lemur catta (ring-tailed lemur) being carried out in this laboratory.) Five male Lemur cattawere tested on their behavioral responses to paired scent stimuli. Responses measured were (1) total investigation time, (2) arm-marking, (3) ABO/BO rubbing, and (4) flehmen. Males showed a strong discrimination between the scent stimuli,giving higher levels of response to female scent on measures 1, 3, and 4. This response suggests an olfactory-related preference by males for female scent under controlled conditions. This preference may be a consequence of the females’ dominance over males and the brevity of estrus in L. catta,both of which would favor such choice behavior.     

Meat eating and predation in captive-born semi-free-ranging Lemur fulvus and caged Lemur macaco

A group of brown lemurs, Lemur fulvus, and a group of black lemurs, Lemur macaco, at the Duke University Center for the Study of Primate Biology and History have been observed to capture and eat birds and lizards. Although vertebrate prey are not unusual for many carnivorous prosimians, folivorous prosimians never have been observed to take vertebrates in the wild and rarely even insects.     

Successful artificial insemination in Lemur fulvus mayottensis

A method is reported for collection of sperm by electrostimulation or prostatic massage in order to carry out artificial in utero insemination in Lemur fulvus mayottensis. Using fresh sperm, one success out of 7 attempts was obtained, although it was achieved with a vesiculectomized male.     

Discrimination between individuals by scent in Lemur fulvus

When a captive Lemur fulvus is habituated to the scent of another L. fulvus by repeatedly presenting it with that individual's scent, and is then presented with the scent of a second individual, the amount of sniffing of the scents increases, indicating that it discriminated between the scents of the two individuals. The two individuals' scents were significantly discriminated in eight of eleven different combinations of scent receiver and pair of scent donors. The two scent donors were always of the same sex and subspecies, and they could be discriminated by members of their own or of another sex or subspecies.     

Differences in rat kidney morphology between males, females and testosterone-treated females.

Kidneys of normal female and male Wistar-Kyoto rats were studied by standard morphological techniques and morphometry in order to evaluate possible differences in the overall kidney morphology between both sexes. Furthermore, we investigated the role of testosterone (DHT) on kidney morphology by treating females with daily DHT injections. Kidney weight and volume in relation to body weight were not significantly different between males and females and were not affected by DHT. Differences were found in the volume distribution among the kidney zones. The cortex was larger in males than in females, whereas the medulla was conspicuously larger in females than in males. The greater volume of the cortex in males was mainly due to a more extensive development of proximal tubules. DHT treatment in females increased the volume of their proximal tubules. Glomerular volume was similar among the three groups. Within the medulla, the difference was most prominent in the inner stripe (14.9% of the total kidney volume in females vs. 8.9% in males) and was also important in the inner medulla (7.0 vs. 4.8%). The absolute epithelial volume of thick ascending limbs in this zone was larger in females than in males. This difference was more pronounced in short loops (approximately 20%) than in long loops (approximately 10%). The values of the DHT-treated females ranged in between. In spite of the greater development of medulla and thick ascending limbs in females, urine concentration was higher in males than in females and maximum urinary concentrating ability after 48 h dehydration was not different between both sexes.     

Adult Male Scent-Marking in Lemur catta and Eulemur fulvus rufus

Scent-marking and olfactory communication are used extensively by prosimians and can provide spatial and temporal records of group movement and behavior. We compare rates of male scent-marking in relation to reproductive seasons, male dominance rank, and habitat use in two related prosimians: Lemur catta and Eulemur fulvus rufus. We collected scent-marking data on adult male Lemur catta at Beza-Mahafaly Reserve (dry forest), and on Eulemur fulvus rufus at Ranomafana National Park (rainforest), Madagascar. In Lemur, rates of overall scent-marking differed significantly by reproductive season, with higher rates occurring in mating and lactation/migration periods, whereas in Eulemur, reproductive season did not appear to affect scent-marking rates. Dominance rank of male Lemur catta did not affect rates of scent-marking. Among male Eulemur fulvus, dominance relations were not apparent; however, 2 of the 5 focal males scent-marked somewhat more frequently during the mating season and also experienced greater mating success. In Lemur catta, higher rates of scent-marking in the mating season may relate to indirect reproductive competition during a period of high aggression, while such mating competition was not as marked in Eulemur fulvus. Furthermore, higher rates of marking in resident male Lemur catta during male migration may correlate with vigilance toward immigrating males. Greater overall scent-marking rates in ring-tailed lemurs may relate to extensive intergroup home range overlap and no area of exclusive use, whereas the red-fronted lemur groups tended to forage in areas of their home range where little-to-no intergroup overlap occurred.     

The oestrous cycle of the brown lemur, Lemur fulvus.

Examination of vaginal smears and observations of the colour and tumescence of the genitalia and discharge of mucus of 9 brown lemurs indicated that the oestrous cycle lasted for 30 days and that cycles occurred between September and July. The timing of cycles of females housed in visual isolation differed from that of females able to see other lemurs, indicating that the oestrous cycle in this species can be influenced by different housing conditions.     

Soil Consumption of Two Groups of Semi-free-ranging Lemurs {Lemur catta and Lemur fulvus)

Soil consumption of two Malagasy lemurs, Lemur catta and Lemur fulvus was observed in an enclosure simulating a natural habitat at Duke University Primate Center (Durham, USA). Soil eaten by L. catta contained more Na than random soil samples. Concentrations of the four major minerals in soil eaten by L. fulvus did not differ from random samples. L. fulvus stopped soil ingestion in summer when they ate large amounts of foliage rich in K and Mg, also in winters after being fed with MgCl₂. It is suggested that, in this study, soil was consumed in relation to its mineral content and not for physical properties related to its structure. Some non physiological factors that might influence food selection are discussed.     

Variation in pelvic size between males and females

Selection intensity and phenotypic variability are inversely related. It has been hypothesized that, owing to opposing selection pressures on pelvic morphology in females between efficiency in locomotion and obstetric adequacy, female pelvic morphology is less variable than that in males. The hypothesis was supported based on data derived from observational methods of sexing pelves (Meindl et al., 1985). The hypothesis was tested in the present study based on a metrical analysis of the true pelvis. The results show that there are no sexual differences in pelvic variability. Consequently, while males and females are equally variable in the dimensions of the true pelvis, the visual cues that osteologists use to sex pelves are more variable in males.     

Beyond odor discrimination: demonstrating individual recognition by scent in Lemur catta

The current study demonstrates, for the first time, the occurrence of olfactory individual recognition in a nonhuman primate species. The empirical demonstration of recognition systems requires 1) a set of cues produced by the sender (expression component), 2) the perception of these cues by the receiver (perception component), and 3) a functional response by the receiver (action component). On the basis of this framework, we analyzed by gas chromatography 35 brachial secretions collected from 10 males of Lemur catta. Moreover, we performed habituation/discrimination tests to demonstrate the perception component, and we designed a specific bioassay, based on territorial competition, to highlight a functional response to individual odors. We demonstrated that recognition of conspecific odors goes beyond the perception of cues other than individuality (familiarity, kin, season, age, and rank) and that the receiver actually forms a mental representation of a specific individual by its scent.     

Study of morphological and cytological parameters indicating oestrus in Lemur fulvus mayottensis

Lemur fulvus mayottensis females were presented each day to vasectomized males. A simultaneous study of parameters of vaginal smears, external genital organs, and the cervix was carried out on the same females. Results from the two methods allow the determination of oestrus, that is, the best period for artificial insemination.     

Responses of Lemur fulvus to Scents of Different Subspecies of L. fulvus and to Scents of Different Species of Lemuriformes

Captive Lemur fulvus were presented with scents of their own subspecies, scents of other subspecies of L. fulvus, and scents of other species of sympatric Lemuriformes. The results suggest that L. fulvus do not distinguish between scents of different subspecies of L. fulvus, and that they do distinguish between scents of their own species and other sympatric species of Lemuriformes.     

Amino acid sequences of the alpha and beta chains of adult hemoglobin of the brown lemur, Lemur fulvus fulvus.

Globin prepared from hemoglobin of the brown lemur (Lemur fulvus fulvus) was separated into alpha and beta chains by chromatography on a CM 52 column. The S-aminoethylated alpha and beta chains were each digested with trypsin and resulting peptides were isolated. The amino acid sequences of the tryptic peptides were established. The ordering of these peptides in the alpha and beta chains was deduced from the homology of their amino acid sequences with that of human adult hemoglobin. The primary structure of brown lemur hemoglobin thus obtained differs from that of human hemoglobin in 15 amino acids in the alpha chain and 26 in the beta chain.     

The role of scent marking in Lemur catta agonistic behavior

Certain forms of marking behavior in Lemur catta have been considered to be aggressive in nature but had not been analyzed specifically in this respect. This study examines the relationship between the occurrence of all forms of marking behavior displayed by a captive group of lemurs and their physical and nonphysical aggressive interactions. All forms of marking behavior, especially males' tail mark and tail wave displays, were found to correlate with aggressive behavior including female-instigated agonism. In comparison, allogrooming, a behavior thought not to have an agonistic component, was not significantly correlated with any marking nor agonistic category. The data suggest that in intersexual interactions male marking behavior is an aggressive but nonphysical substitute for physical aggression toward females who have generally been regarded as dominant to males in this species.     

Evolutionary conflicts of interest between males and females

Sexual conflict arises from differences in the evolutionary interests of males and females and can occur over traits related to courtship, mating and fertilisation through to parental investment. Theory shows that sexual conflict can lead to sexually antagonistic coevolution (SAC), where adaptation in one sex can lead to counter-adaptation in the other. Thus, sexual conflict can lead to evolutionary change within species. In addition, SAC can--through its effects on traits related to the probability of mating and of zygote formation--potentially lead to reproductive isolation. In this review, I discuss that, although sexual conflict is ubiquitous, the actual expression of sexual conflict leading to SAC is less frequent. The balance between the benefits and costs of the manipulation of one sex by the other, and the availability of mechanisms by which conflict is expressed, determine whether actual sexual conflict is likely to occur. New insights address the relationship between sexual conflict and conflict resolution, adaptation, sexual selection and fitness. I suggest that it will be useful to examine systematically the parallels and contrasts between sexual and other evolutionary conflicts. Understanding why some traits, but not others, are subject to evolutionary change by SAC will require data on the mechanisms of the traits involved and on the relative benefits and costs of manipulation and resistance to manipulation.