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PubMed2004

Changes in social interactions during adolescence in male mandrills (Mandrillus sphinx).

The adolescent period in male mandrills extends from the time the testicles descend (at the age of 3-4 years) to the time adult characteristics develop (at the age of 10 years), and is thus one of the longest adolescent periods in cercopithecines. In this short cross-sectional study of 11 male mandrills (4.7-9.1 years old), we analyzed social behavioral patterns to investigate partner preference and changes in types of interactions throughout puberty. The mandrills were separated into two clusters on the basis of all of the social interactions scored, as well as the age and sex of the protagonist. During early to mid puberty, immature individuals interacted preferentially with other male adolescents and juveniles. Playing was an important activity, and some affiliative interactions with juveniles were observed. Older adolescents interacted more with adult males and females. These older adolescents were predominantly aggressive toward other adolescents, females, and juveniles, and showed little or no affiliative or playful behaviors. These results indicate a shift in social partners: older males interacted more frequently with adult males, and their behavior involved more aggression and less submission compared to younger adolescents, which showed predominantly submissive and playful behavior. These changes are consistent with preparation for dispersal and future intermale competition.

Age Factors↗
PubMed2001

Arrested development of secondary sexual adornments in subordinate adult male mandrills (Mandrillus sphinx).

Previous studies of semifree-ranging mandrills identified two morphological and social variants of the adult male, based on behavioral and secondary sexual characteristics. "Fatted" males are social, with highly developed sex skin coloration, large testes, high plasma testosterone levels, and fat rumps; while "nonfatted" males are peripheral or solitary, with paler sex skin, smaller testes, lower plasma testosterone, and slimmer rumps. We present a detailed study of morphology and group association for 10 adult male mandrills, living in two semifree-ranging groups in Gabon, in order to relate differences between males to dominance rank. The results show that rather than existing as two distinct morphotypes, male mandrills represent a continuous spectrum of possibilities between social males with fully developed secondary sexual characteristics, and solitary males with muted secondary sexual characteristics. Alpha males (N = 2) had the highest testosterone levels, the most colorful sex skin, and the most active sternal glands, and were the only males to spend 100% of their time with the social group. Rank relationships between nonalpha males (N = 8) were not always clear, but all subordinate males had lower testosterone levels and less development of the secondary sexual adornments, and were less group-associated than alpha males. These findings suggest that only alpha males have sufficient testosterone to develop full secondary sexual characteristics, and we propose possible socioendocrine mechanisms underlying the suppression of testosterone and secondary sexual development in subordinate adults. We discuss differences in secondary sexual development in relation to reproductive strategies, and discuss the evolution of alternative reproductive morphs in primates.

Animals↗
PubMed2001

Growth and ontogeny of sexual size dimorphism in the mandrill (Mandrillus sphinx).

We present body mass (N = 419) and crown-rump length (CRL, N = 210) measurements from 38 male and 49 female mandrills born into a semifree-ranging colony in order to describe growth from birth to adulthood, and to investigate maternal influences upon growth. Adult male mandrills are 3.4 times the body mass, and 1.3 times the CRL, of adult females. Body mass dimorphism arises from a combination of sex differences in length of the growth period (females attain adult body mass at 7 years, males at 10 years) and growth rate. Both sexes undergo a subadult growth spurt in body mass, and this is much more dramatic in males (peak velocity 551 g/months +/- 89 SEM at 84-96 months). CRL dimorphism arises from bimaturism (females attain adult CRL at 6 years, males after 10 years), and neither sex shows a particular subadult growth spurt in CRL. Sexual size dimorphism thus represents important time and metabolic costs to males, who mature physically approximately 3-4 years after females. Considerable interindividual variation occurs in the size-for-age of both sexes, which is related to maternal variables. Older mothers have heavier offspring than do younger mothers, and higher-ranking mothers have heavier offspring than do lower ranking mothers. Mass advantages conferred upon offspring during lactation by older and higher-ranking mothers tend to persist postweaning in both sexes. Thus maternal factors affect reproductive success in both sexes, influencing the age at which offspring mature and begin their reproductive career.

Age Factors↗
PubMed2001

Changes in the secondary sexual adornments of male mandrills (Mandrillus sphinx) are associated with gain and loss of alpha status.

Two semifree-ranging mandrill groups, inhabiting large, naturally rainforested enclosures in Gabon, were studied to measure morphological, endocrine, and behavioral changes that occurred when adult males rose, or fell, in dominance rank. Gaining alpha rank (N = 4 males) resulted in increased testicular size and circulating testosterone, reddening of the sexual skin on the face and genitalia, and heightened secretion from the sternal cutaneous gland. Blue sexual skin coloration was unaffected. New alpha males increased in rump "fattedness," but not in body mass, and spent more time associated with other group members, rather than ranging alone. Loss of alpha position (N = 4 males) resulted in less pronounced effects than those that occurred after males had risen to alpha positions. Deposed alpha males showed decreased testicular volume, decreased body mass, a reduction in the extent of red (but not blue) sexual skin coloration, and decreased sternal gland activity. Deposed males did not decrease in the brightness of sex skin coloration. These results demonstrate that male-male competition and rank reversals have remarkable effects upon testicular function, secondary sexual traits, and behavior in the adult male mandrill. Secondary sexual traits respond to changes in male social status and therefore may be important as intrasexual signals of dominance rank.

Animals↗
PubMed1992

Testicular function, secondary sexual development, and social status in male mandrills (Mandrillus sphinx).

Positive correlations between dominance rank and plasma testosterone levels have been described for adult males of several primate species in captivity, but the relevance of such observations to free-ranging animals is unclear. CIRMF in Gabon maintains a breeding group of 45 mandrills in a six hectare, naturally rainforested enclosure. This study describes correlations between dominance rank (in agonistic encounters), levels of plasma testosterone, testicular volume, body weight, and development of secondary sexual characteristics (red and blue sexual skin on the muzzle and rump areas) in male mandrills under semifree ranging conditions. Two morphological and social variants of adult male mandrill were identified. Large-rumped or fatted adult males (n = 3) remained in the social group and exhibited maximal development of sexual skin coloration as well as large testicular size and highest plasma testosterone levels. By contrast, slimmer-rumped or nonfatted males (n = 3) lived a peripheral or solitary existence and these exhibited less development of their secondary sexual coloration and had smaller testes and lower plasma testosterone levels. Longitudinal studies of gonadal development in these six males revealed that testicular volumes and plasma testosterone levels increased most rapidly during pubertal development (4-5 years of age) in the three animals which proceeded to the fatted condition. These included the highest ranking, group-associated male which exhibited the most intense sexual skin coloration and had higher testosterone levels, although this was not correlated with testicular volume. This study shows that in the male mandrill social factors and reproductive development are interrelated.(ABSTRACT TRUNCATED AT 250 WORDS)

Aggression↗
PubMed1982

Survival of Loa loa following transplantation from drills (Mandrillus leucophaeus) into jirds (Meriones unguiculatus): parasitology and pathology.

Two drills infected with Loa loa maintained a microfilaraemia for four and a half years ranging from less than 1 mf/100 microliters to 1150 mf/100 microliters. No significant tissue reactions to the adult worms were seen at autopsy. Adult worms were transplanted into the peritoneal cavities of naive jirds when a persistent microfilaraemia first developed by 17 days. Retransplantation of adult worms into naive jirds produced a microfilaraemia and microfilariae in the peritoneal cavities of three out of five animals. These three animals were all negative for circulating parasites by eight and a half months. The tissue reactions to the worms in the jirds are described, including a granulomatous response surrounding adults and a myositis involving microfilariae.

Animals↗
PubMed2003

High levels of SIVmnd-1 replication in chronically infected Mandrillus sphinx.

Viral loads were investigated in SIVmnd-1 chronically infected mandrills and the results were compared with those previously observed in other nonpathogenic natural SIV infections. Four naturally and 11 experimentally SIVmnd-1-infected mandrills from a semi-free-ranging colony were studied during the chronic phase of infection. Four SIVmnd-1-infected wild mandrills were also included for comparison. Twelve uninfected mandrills were used as controls. Viral loads in all chronically infected mandrills ranged from 10(5) to 9 x 10(5) copies/ml and antibody titers ranged from 200 to 14,400 and 200 to 12,800 for anti-V3 and anti-gp36, respectively. There were no differences between groups of wild and captive mandrills. Both parameters were stable during the follow-up, and no clinical signs of immune suppression were observed. Chronic SIVmnd-1-infected mandrills presented slight increases in CD20+ and CD28+/CD8+ cell counts, and a slight decrease in CD4+/CD3+ cell counts. A slight CD4+/CD3+ cell depletion was also observed in old uninfected controls. Similar to other nonpathogenic models of lentiviral infection, these results show a persistent high level of SIVmnd-1 replication during chronic infection of mandrills, with minimal effects on T cell subpopulations.

Animals↗
PubMed2003

Parasitological and immunological effects induced by immunization of Mandrillus sphinx against the human filarial Loa loa using infective stage larvae irradiated at 40 Krad.

Six mandrills were immunized with 150 Loa loa infective stage larvae (L3) irradiated with 40 Krad, and challenged with 100 L3, 60 days after initial vaccination. The parasitological outcome of this immunization was compared to results from six mandrills infected with normal L3. No clear association was seen between vaccination and microfilaremia until day 245 when a significant drop in the level of microfilaria occurred in vaccinated compared to infected animals (5 vs 10 mf/ml; p = 0.012). A one-year follow-up of the humoral immune response showed a strong adult, microfilariae (Mf) and L3 specific IgG response, with distinct profiles for each extract. In immunized animal a significant decrease in antibody level was systematically observed between days 90-145 for the anti-L3 and anti-adult IgG. However, in the same group anti-Mf antibody levels that peaked around 160-175 days post-challenge, were inversely correlated with the decrease in Mf density between day 200 and day 386. These results suggest that immunization with irradiated L3 using these specific conditions may affect the appearance of Mf.

Animals↗
PubMed1998

Phylogenetic analysis of SIV and STLV type I in mandrills (Mandrillus sphinx): indications that intracolony transmissions are predominantly the result of male-to-male aggressive contacts.

Natural SIVmnd and STLVmnd infections of mandrills in a colony at the Centre International de Recherches Médicales de Franceville (CIRMF) in Gabon were investigated by genetic analysis to determine the extent of intracolony transmission. SIVmnd pol sequence analysis indicates that the six strains present in the colony belong to the SIVmnd lentivirus subgroup previously defined according to the only available prototype sequence (SIVmndGB1), which originated from the same colony. The intraanimal nucleotide diversity (1.1-3.1%) was similar in range to that reported in individuals infected by other HIV/SIVs. The interanimal diversity (0.5-4.3%) was not significantly different from that observed in each individual mandrill, indicating an epidemiological link among the SIVmnd isolates of distinct animals within the colony. Phylogenetic analysis of these isolates, together with seroepidemiological and behavior surveillance within the colony, indicates a predominant male-to-male transmission of SIVmnd that probably occurred during bouts of interanimal aggression. Moreover, our results suggest one case of vertical transmission of SIVmnd from a naturally infected founder female to one of her six offspring. The first genetic analysis of STLV isolates from mandrills is also reported here. Partial tax/rex sequences were used to evaluate the diversity between seven STLVmnd isolates and their phylogenetic relationships with other known strains of human and nonhuman primate T cell leukemia virus, types I and II (PTLV-I/II). They all belong to the PTLV-I subtype, but two genetically distinct STLVmnd groups were evidenced within the mandrill colony. The phylogenetic analyses of the STLVmnd isolates, together with seroepidemiological and behavior surveillance of the mandrills, indicate that intracolony transmissions of STLVmnd are also predominantly the result of male-to-male aggressive contacts.

Aggression↗
PubMed1998

A novel simian immunodeficiency virus (SIVdrl) pol sequence from the drill monkey, Mandrillus leucophaeus.

The drill monkey has been shown by serology and PCR to harbor a unique simian immunodeficiency virus (SIVdrl). A pol sequence, amplified from uncultured peripheral blood cells, is most closely related to the equivalent SIV sequences from the red-capped mangabey (SIVrcm), the sabaeus African green monkey (SIVagmSAB), and the chimpanzee (SIVcpz) and to the human immunodeficiency virus type 1 (HIV-1) sequence of humans. It is as yet unclear whether SIVdrl has a mosaic genome like SIVrcm and SIVagmSAB, is a member of the SIVcpz/HIV-1 lineage, or represents a novel primate lentivirus lineage.

Amino Acid Sequence↗
PubMed1992

Development from birth to sexual maturity in a semi-free-ranging colony of mandrills (Mandrillus sphinx) in Gabon.

This report presents information collected over 7 years (1983-1990) in Gabon, on a breeding group of 14, increasing to 45, mandrills maintained in a rainforest enclosure. Under these conditions, a seasonal cycle of mating (June-October) and birth (January-May) occurred. Females began to exhibit sexual skin swellings at age 2.75-4.5 years (3.6 +/- 0.6 years, mean +/- SD; n = 10) and first delivered offspring when 3.25-5.5 years old (4.4 +/- 0.8 years; n = 9). Gestation periods ranged from 152 to 176 days (167 +/- 9 days; n = 6 accurately dated pregnancies) and interbirth intervals from 11 to 15 months (12.4 +/- 1.3 months; n = 15). Females could reproduce 2 years before attaining adult body weight (10-15 kg) and complete dental eruption by 5.0-5.5 years. Males, by contrast, developed more slowly, reaching adult body weight (30-35 kg) and testicular volume (volume of left testis: 25-30 ml) at 8 years. Consistently high circulating testosterone concentrations (8.17 +/- 2.0 ng ml-1) could be measured by 9 years of age. Fully developed males exhibited fatting of the rump and flanks, as well as striking sexual skin coloration and an active sternal cutaneous gland; little expression of these features was evident during pubertal development. Marked individual age differences occurred with regard to the onset and complete development of these features, suggesting possible interactions between social environment and physical maturation.

Animals↗