Genotyping from semen of wild Japanese macaques (Macaca fuscata)

The noninvasive collection of animal cells is crucial for DNA analyses in wild populations that cannot be disturbed by capture. We describe the collection of 68 semen samples following copulation and masturbation events in wild habituated and nonhabituated troops of Japanese macaques on the protected island of Yakushima. We used this DNA to amplify 390 base pairs (bp) of the mitochondrial DNA control region in 16 individuals from eight troops, and found a monomorphic pattern in agreement with the low variability imposed by geographic isolation and female philopatry. We also amplified two microsatellite loci from samples collected after the resident males of a focal troop had copulated with different females. We found several different allele combinations in samples collected after the observed mating of a single male, indicating the presence of contaminant DNA, presumably from males that had previously mated with the same female. This discovery made it impossible to assign a given sample to a specific male except when the samples were recovered after masturbation events. Thus, it was not possible to test for kinship or estimate allele frequencies from the semen samples. The mixing of semen, and the pattern of sample collection observed in morphologically identified individuals support the notion that strong mating and sperm competition exists among resident and nonresident males.     

Urinary steroid hormone analysis of ovarian cycles and pregnancy in mandrills (Mandrillus sphinx) indicate that menses,copulatory behavior,sexual swellings and reproductive condition are associated with changing estrone conjugates (E1C) and pregnanediol‐3‐glucuronide (PdG)

The objective of this study was to determine if sexual swellings in mandrills (Mandrillus sphinx) are a reflection of reproductive endocrine state. Urine samples were assayed using an enzyme immunoassay measuring pregnanediol‐3‐glucuronide (PdG) and estrone conjugates (E₁C). Hormone patterns of ovarian cycles, pregnancy and lactation were characterized and compared with sexual swellings and copulations relative to menses and peak E₁C. Cycle lengths averaging 28.7 days and pregnancy length of 181 days determined by hormonal and sexual swelling measures were similar to those reported in other Old World primate species. First day of copulation was observed during rising E₁C concentrations and preceded observations of peak swelling by 1–2 days. Observations of peak sexual swellings occurred at or on the day after peak E₁C and decreased following the ovulatory increase in PdG. Observations of menses and sexual swellings are a useful method to track mandrill ovarian cycles and can assist zoos in determining the reproductive state of females in their collections. Zoo Biol 27:320–330, 2008. © 2008 Wiley‐Liss, Inc.     

Relationship between sexual interactions and the timing of the fertile phase in captive female Japanese macaques (Macaca fuscata)

Japanese macaques live in multi‐male/multi‐female social groups in which competition between males, female mate choice, and alternative male mating strategies are important determinants of mating and reproductive success. However, the extent to which adult males rely on female behavior to make their mating decisions as well as the effect of social rank on mating success are not clear as results are inconclusive, varying from study to study. In this study, we combined behavioral and endocrine data of 14 female Japanese macaques to examine the relationship between ovarian cycle phase and frequency of sexual behaviors, and to investigate how social rank influences sexual behavior in this species. We found that there was no increase in female proceptive behaviors during the fertile phase of the ovarian cycle, suggesting that female behaviors did not clearly signal the probability of conception. In spite of that, the frequencies of ejaculatory copulations were highest during this phase, indicating that the attractivity of females increased significantly during the period with higher probability of conception. Males, and especially the highest ranking male, were able to discriminate females nearing ovulation and to concentrate their mating effort, implying that the timing of ovulation was not concealed from them. The α male seemed able to monopolize most female matings, which is probably due in part to the low number of females simultaneously ovulating and to the limited number of inconspicuous places that the lower ranking males have to mate with females and avoid α male aggression. All together, these results suggest that different males may have access to different signals of ovulation and/or are differentially restrained as to how they can act on that information. The exact nature of the estrogen‐related cues males use to recognize female reproductive status, and to what extent males use them warrants further investigation. Am. J. Primatol. 71:868–879, 2009. © 2009 Wiley‐Liss, Inc.     

Changes of urinary steroid conjugates and gonadotropin excretion in the menstrual cycle and pregnancy in the Yunnan snub-nosed monkey (Rhinopithecus bieti).

The Yunnan snub-nosed monkey (Rhinopithecus bieti) is one of the most endangered species in the world, and it is endemic to China. According to our knowledge, there was no information on reproduction for this species. The present study was designed to understand the characteristics of reproductive hormone secretion during the menstrual cycle and pregnancy of this species by monitoring urinary estrone conjugate (E1C), pregnanediol-3-glucuronide (PdG), bioactive follicle-stimulating hormone (FSH), and luteinizing hormone (LH). The urine samples were collected each day from four adult females for eight menstrual cycles, and once in 3 days during pregnancy (three full-term pregnancies, one mid-term abortion). The steroid conjugate was tested by radioimmunoassays (RIAs), and bioactive FSH and LH levels were measured in vitro by the sensitive bioassays granulosa cell aromatize bioassay (GAB) and rat interstitial cell testosterone (RICT), respectively. The results showed that: 1) E1C presented a preovulatory peak (183.9 +/- 8.6 ng/mgCr) followed by a definite elevation of PdG; 2) PdG in the luteal phase (754.4 +/- 30.6 ng/mgCr) was three- to fivefold higher than during the corresponding follicular phase (198.3 +/- 11.4 ng/mgCr); 3) the peaks of bio-LH and bio-FSH were on the same day, while the E1C peak was 1 or 2 days before the peaks for these two hormones; 4) bio-FSH levels were higher in the follicular phase than in the luteal phase, and bio-LH levels elevated slightly in the luteal phase; 5) the mean cycle length was 23.6 +/- 3.5 days (n = 3) based upon successive urinary LH peaks; 6) based on the interval from the day of E1C peak to the day of parturition, the gestation was 203.7 +/- 2.5 days (n = 3); and 7) both E1C and PdG increased and remained high after pregnancy, with a sharp decrease in basal levels following parturition or mid-term abortion. The results suggested that the pattern of reproductive hormones for R. bieti is similar to that of other Old World monkeys, but the concentration of the hormones is different from that of other species. This species has a longer progestation period, which may be related to its classification status.     

Measurement of urinary and fecal steroid metabolites during the ovarian cycle in captive and wild Japanese macaques, Macaca fuscata

We measured the concentration of steroid hormones from urine, feces, and blood samples of two captive Japanese macaques, Macaca fuscata, during nonconceptive ovarian cycles to compare the patterns of the excreted steroids with those of circulating steroids. Urine and feces were analyzed for estrone conjugates (E1C) and pregnanediol-3-glucronide (PdG) using enzyme immunoassays (EIAs), while plasma was analyzed for estradiol-17beta(E2), progesterone (P), and luteinizing hormone (LH) using radioimmunoassays (RIAs). Urinary and fecal E1C and PdG levels were approximately parallel to plasma E2 and P levels, respectively. The E1C profiles of daily urinary and fecal samples revealed a midcycle peak, followed by a sustained PdG increase lasting up to two weeks from the E1C peak. A fecal E1C peak was one day later than the urinary E1C peak. One of the captive females exhibited a discrete plasma LH peak, one indicator that ovulation has occurred, on the day following the urinary E1C peak, i.e., the same day of fecal E1C peak. We measured excreted steroids in nine wild females and determined the timing of ovulation by comparing fecal steroid profiles to those obtained in captive monkeys. Data from wild females indicated that eight of nine females conceived during their first ovulatory cycle of the sampling period, whereas the remaining female failed to conceive during the sampling period even though she ovulated. In the eight females that conceived, E1C increased again following the detected or estimated E1C peak, with levels comparable to the preovulatory peak levels, and sustained elevations of PdG for over 40 days. These data illustrate that the urinary and fecal profiles of ovarian steroid excretion obtained through the application of these noninvasive techniques provide an accurate approach for monitoring conceptive and nonconceptive ovarian cycle in captive and free-living Japanese macaques.     

Habitual hot-spring bathing by a group of Japanese macaques (Macaca fuscata) in their natural habitat

Japanese macaques (Macaca fuscata) in a free-ranging group in Jigokudani valley, Nagano prefecture, are known to bathe in a hot spring. We used scan sampling in a study aimed at elucidating the causal factors and possible social transmission of this behavior. From 1980-2003, 31% of a total 114 females in the group habitually bathed in the hot spring. The habit was more widespread in dominant matrilines than in subordinate matrilines. Infants whose mothers bathed were more likely to bathe than infants of mothers who did not bathe. The number of monkeys bathing was clearly influenced by ambient air temperature. More monkeys bathed in the hot spring in winter than in summer. The results support the thermoregulation hypothesis of hot-spring bathing. Bathing behavior varies among age and sex categories of monkeys, with adult females and juveniles bathing more often than adult males and subadults. We compared hot-spring bathing with other thermoregulatory behaviors in various primate populations.     

Relationship between ovarian cycle phase and sexual behavior in female Japanese macaques (Macaca fuscata)

We conducted behavioral observations simultaneously with fecal sample collection on eight nonlactating females 2-3 times per week, October 1997-March 1998, to examine the relationship between ovarian hormones and the sexual behavior of female Japanese macaques (Macaca fuscata) during the mating season. We analyzed samples by enzyme immunoassay for fecal hormone levels. Hormone profiles of estrone-glucuronide (E1) and pregnanediol-glucuronide (PdG) were used to separate ovarian cycles into three phases (follicular, periovulatory, and luteal). Hormonal profiles indicate average cycle lengths of 27.6 +/- 4.2 days (+/- SD; n = 26). Average lengths of the luteal and follicular phases were 12.3 +/- 3.8 days (+/- SD) and 8.3 +/- 3.4 days (+/- SD), respectively. We observed female Japanese macaques engaging in sexual activity throughout the ovarian cycle, with the highest rates occurring during the follicular and periovulatory phases as compared to the luteal phase. The attractivity of female Japanese macaques increased significantly during the follicular and periovulatory phases of the ovarian cycle, when E1 levels are peaking and PdG levels drop to baseline. In addition, females displayed a significant increase in proceptive behavior during the follicular and periovulatory phases. Grooming bouts, as well as proximity between female and male macaques, also increased significantly during the follicular and periovulatory phases. We conclude that fluctuating levels of ovarian hormones in different phases of the cycle are significantly associated with variable rates of copulatory and pericopulatory behaviors in these Japanese macaque females.     

Environmental temperature and reproductive seasonality in Japanese macaques (Macaca fuscata)

This study demonstrates that the reproductive seasonality ofMacaca fuscata seems to be more affected by environmental temperature than by photoperiod. Mean conception dates for 25 groups of Japanese macaques species did not correlate with latitude. Instead, they were positively related to mean fall and winter temperatures and negatively related to the magnitude of the decrease in the mean temperature from summer to fall. Evidence from transplanted groups supports the hypothesis that environmental temperature is a decisive factor in determining the timing of mating activities of Japanese macaques. These results are also consistent with the concept that, in temperate zones, environmental temperature is probably the best indicator of local climatic characteristics.     

Seasonal and reproductive variation in body condition in captive female Japanese macaques (Macaca fuscata)

The geographic distribution of Japanese macaques includes populations with the most northern range of any primate species. Not surprisingly, females of this species are characterized by physiological adaptations and unique fat deposition mechanisms that facilitate their survival through the sometimes‐harsh seasonal conditions of temperate climates, as well as sustaining the metabolic costs of mating, pregnancy, and lactation. Here, we explore the relationship between nutritional status, seasonality, and reproductive status using anthropometric and leptin measures from 14 captive female Japanese macaques. No seasonal patterns were found in the levels of leptin, but there were differences between seasons in anthropometric measures, specifically between the beginning and the end of the mating season. Females gained weight and accumulated energy reserves in fall to prepare for mating activity, and to survive the severe conditions of winter, which is also the period of gestation if pregnancy occurs. Lactating females had larger total skinfolds relative to nonlactating individuals, and females with older babies at the beginning of the mating season had larger abdominal skinfolds than did those with younger babies. There was a relationship between the likelihood of conception and nutritional status, with females that conceived during one mating season being in better condition at the end of their previous mating season. Together, these results suggest that, even in captive settings, seasonal breeding has a cost on the energetic demands of mating, and that higher condition (i.e. fatter) females could afford the demands of lactation and reproduced more rapidly. Am. J. Primatol. 72:277–286, 2010. © 2009 Wiley‐Liss, Inc.     

Puberty in male Japanese macaques (Macaca fuscata): Social and sexual behavior in a confined troop

The social and sexual behaviors of four groups of males (4, 5, 9, and 10 years old) were compared throughout one complete mating season in a confined troop of Japanese macaques (Macaca fuscata). The aim of this research was to document social behavior changes that occurred during adolescence and to relate them to changes in sexual behavior that occurred at puberty. The 4-year-old males all mounted females and ejaculated but they had significantly fewer ejaculations and female partners than did the older males. The 4-year-old males also showed a pattern of delayed development in tail carriage and courtship, and they played more frequently than the older males. There were no significant differences in the frequency of aggression among the groups, but both 4-year-old and 5-year-old males were displaced by adult males and females more frequently than were the older males. We concluded that the development of adult patterns of social behavior in this genus is not climactic, but occurs slowly one to two years after physiological puberty has been reached.     

Extra-large cluster formation by Japanese macaques (Macaca fuscata) on Shodoshima Island, central Japan, and related factors

Japanese macaques on Shodoshima Island habitually form very large rest clusters, in which 50+ or even 100+ individuals huddle together. This behavior is not seen in any other populations of the species. Mean cluster sizes of two groups of Shodoshima monkeys are three and four in summer and 17 and 16 in winter, respectively. A maximum of 137 individuals have been seen to huddle in one cluster. It is difficult to explain the extra large clusters on Shodoshima only as an adaptive behavior against cold, since Shodoshima is relatively warm in the range of habitats for Japanese macaques. Compared with other groups of Japanese macaques, Shodoshima monkeys show: more frequent affinitive interactions, shorter inter-individual distance, more frequent ignoring of exclusion, more frequent aggression, less intense aggression, and more frequent counter-aggression. These characteristics suggest that the Japanese macaques on Shodoshima have relaxed dominant relations. The specific social organization of Shodoshima monkeys may sustain the formation of extra large clusters. Inter-group comparisons suggest that the social structure of Japanese macaques might be highly plastic, and that Shodoshima monkeys have less despotic, more tolerant social relations than typically reported for this species.     

Seasonal changes in spermatogenic cell degeneration in the seminiferous epithelium of adult Japanese macaques (Macaca fuscata fuscata)

The degenerating pattern of spermatogenic cells in the seminiferous tubule of Japanese macaques was studied to clarify a relationship between seasonal changes of reproductive performances and cytological findings in the Japanese macaque. For light microscopy, testis samples were obtained from five adult animals by biopsy in April (nonmating season) and October (mating season). For electron microscopy, specimens from four additional macaques were used. Degenerating cells were found in all steps of spermatogenesis. In stages I to V of the cycle of the seminiferous epithelium, morphologically atypical pachytene spermatocytes were observed in 14.7 and 10.0% of the cells in the nonmating and mating seasons, respectively, although the difference in percentage was not significant. Mature spermatids with atypical features in those stages occupied 59.6% of the cells in the nonmating season, which significantly decreased to 34.1% in the mating season. These results imply that the seasonal change of sperm production is related, at least in part, to the process of degeneration of the spermatogenic cells in this species.     

Energetic consequences of seasonal breeding in female Japanese macaques (Macaca fuscata)

Japanese macaques inhabit a relatively cold environment and females of this species could have developed strategies of energy economy to face the sometimes-harsh seasonal conditions of temperate climates, as well as reproductive costs, and thus regulate their energy balance. Here, we explore the relationship between nutritional status, body composition, seasonality, and reproductive status using isotope-labeled water, anthropometric measurements, and leptin assays from 14 captive female Japanese macaques. Our results indicated that body mass provided the best predictor of fat-free mass and fat mass. These females varied in estimated percent body fat between 8 and 25% (18% on average at the beginning of the mating season and 13% during the birth season). Higher body mass and body fat content were observed at the beginning of the mating season, which supports the hypothesis that individual females need to attain a sufficient physical condition to cover energy costs associated with mating activity, and to survive under severe ecological conditions in winter with high thermoregulatory costs. We found a relationship between conception rates and energetic condition or body fat, with females that conceived during one mating season being fatter after the end of their previous mating season. Together, these results suggest that, even in captive settings with constant food availability, seasonal breeding entails relatively high energy costs, and that females with higher energy status could invest more in reproductive activities and could afford to reproduce more rapidly.     

Hypervariable microsatellite loci in the Japanese macaque (Macaca fuscata) conserved in related species

We describe seven polymorphic microsatellites isolated from a Japanese macaque (Macaca fuscata) genomic library selected for (GT)_n content. The primer sets amplified from four to 11 different alleles in a sample of 14 Japanese macaques from nine different sites along the central and southern distribution of the species. These heterologous primers also detected variability in four other cercopithecine species. Am. J. Primatol. 43:357–360, 1997. © 1997 Wiley-Liss, Inc.     

How social relationships influence a monkey's choice of feeding sites in the troop of Japanese macaques (Macaca fuscata fuscata) on Koshima islet

When the individual Japanese macaques of the Koshima troop feed on natural food, they usually feed alone. In situations where animals usually feed without other animals, there is a possibility that subordinate animals may avoid feeding sites at which dominant animals are feeding. This paper examines whether social relationships such as kinship or dominance exert any influence on an animal's choice of feeding sites, by analyzing episodes in which an animal approached and climbed into a tree where other animals were. As a result, it was found that social relationships did not influence whether an animal climbed into a tree where other animals were feeding, and that no particular age-sex pair co-fed. Agonistic interactions frequently occurred when the inter-individual distance was less than 1 m. From these findings, the feeding sites were divided into two spaces: (1) a tolerance feeding space, and (2) an intolerance feeding space. It is presumed that animals can feed without entering others' intolerance feeding spaces when food is abundant, as it was in the present study period. Thus social relationships do not influence an animal's choice of feeding sites in such a situation.     

Female rank and reproductive success among arashiyama B Japanese macaques (Macaca fuscata)

Five hypotheses that related female rank and reproductive success were tested in an intact troop of free-ranging, provisioned, Japanese macaques. The hypotheses stated that high-ranking females (1) begin parturition earlier in life than low-ranking females; (2) produce more offspring than low-ranking females; (3) give birth during some optimal time during the birth season to a greater extent than low-ranking females; (4) experience less infant mortality than low-ranking females;and (5) more frequently produce male offspring, while low-ranking females more frequently produce female offspring. A statistical analysis of the data which included three birth seasons and 55 adult females and 34 pubescent females, all of known age, rank, and matrifocal membership in the Arashiyama B troop, revealed few significant results. An association was found between the rank of the matrifocal unit and the age of first birth. However, the relationship was the reverse of hypothesis 1, i.e., females of the lower-ranking matrifocal units began parturition earlier than females of higher-ranking matrifocal units. Therefore, in this troop of Japanese monkeys— where alternative feeding strategies existed— there was little association between female rank and reproductive success.     

Measuring male-female relationships during the mating season in wild Japanese macaques (Macaca fuscata yakui)

Heterosexual relationships during one mating season were examined in a wild troop of Japanese macaques (Macaca fuscata yakui) on Yakushima Island, Japan. Validation tests of putative mate choice behaviors demonstrated that female initiation and maintenance of proximity, female lookback at the male, and sexual presents to the male, were associated with increased mating. Male grooming the female was also associated with increased mating. Ten dyadic social behaviors were subject to principal components analysis to empirically define behavioral dimensions of male-female relationships. The analysis yielded four relationship dimensions: ‘Mutual Choice and Male Coercion,’ ‘Female Choice’ (two types), and ‘Mutual Choice’ Dyads tended to be characterized by more than one dimension. The results suggested that females sought matings with multiple males of various dominance ranks. Female relationships with high ranking males contained elements of male coercion and mate guarding, however, because these males attempted to inhibit females from mating with lower ranking males. The correlation between each relationship dimension and mating success depended, in part, on the dominance rank of males. Relationships involving high ranking males, which were most likely to contain elements of male coercion and mate guarding, were associated with mating success. Relationships involving low ranking males, which usually lacked such coercive elements. were less strongly correlated with mating success. These results, obtained from a wild troop, are compared to those previously obtained in captive and provisioned groups of Japanese macaques.     

Seasonal changes in the spermatogenic epithelium of adult Japanese macaques (Macaca fuscata fuscata)

A histological study was undertaken to clarify seasonal changes in the spermatogenic epithelium of Japanese macaques. Testicular tissue samples were excised by biopsies from five adult laboratory-maintained males in mating and non-mating seasons. The samples were fixed with Bouin's solution, embedded in paraffin, and stained with PAS and hematoxylin. Microscopic observations on cross-sections of seminiferous tubules revealed that the seminiferous epithelium in the mating season was thicker than in the non-mating season. PAS-stained granules were found in some of the dark A-type spermatogonia, which significantly increased in the non-mating season. Spermatids of the steps preceding the appearance of the acrosomic cap in stages I to III were observed significantly more often than those in the step coinciding with the formation of the acrosomic cap in stage IV. In stage I, the ratio of mature spermatids or spermatozoa to immature spermatids in the mating season was higher than that in the non-mating season. These findings suggest that spermiogenesis, as well as spermatocytogenesis, is inhibited in the non-mating season.