Hormonal correlates of reproductive seasonality in wild female hanuman langurs (Presbytis entellus)

Pregnancy diagnosis and sex identification with urinary glycopatterns of two mammal species

Glycome in urine could be promising biomarkers for detecting pregnancy diagnosis and sex noninvasively for animals, especially for rare species. We explore the applicability of grouping golden snub-nosed monkeys by sex or diagnosing pregnancy based on their urinary glycopatterns, which are determined via lectin microarray combining mass spectrometry analysis. Sprague-Dawley rats are used to verify whether this approach and whether the glycomic biomarkers can be generalized to other mammalian species. The results show that, for both species, lectin microarray combining mass spectrometry can distinguish individuals' pregnancy status and sex; significant differences are found in the types, amounts, and terminal modification of glycans between pregnant and non-pregnant females and between females and males. This indicates the approach could be generalized to other mammalian species to group sex and detect pregnancy, yet the glycopatterns appear to be species-specific and markers developed from one species may not be directly applicable to another.

Towards understanding paleoclimate impacts on primate de novo genes

De novo genes are genes that emerge as new genes in some species, such as primate de novo genes that emerge in certain primate species. Over the past decade, a great deal of research has been conducted regarding their emergence, origins, functions, and various attributes in different species, some of which have involved estimating the ages of de novo genes. However, limited by the number of species available for whole-genome sequencing, relatively few studies have focused specifically on the emergence time of primate de novo genes. Among those, even fewer investigate the association between primate gene emergence with environmental factors, such as paleoclimate (ancient climate) conditions. This study investigates the relationship between paleoclimate and human gene emergence at primate species divergence. Based on 32 available primate genome sequences, this study has revealed possible associations between temperature changes and the emergence of de novo primate genes. Overall, findings in this study are that de novo genes tended to emerge in the recent 13 MY when the temperature continues cooling, which is consistent with past findings. Furthermore, in the context of an overall trend of cooling temperature, new primate genes were more likely to emerge during local warming periods, where the warm temperature more closely resembled the environmental condition that preceded the cooling trend. Results also indicate that both primate de novo genes and human cancer-associated genes have later origins in comparison to random human genes. Future studies can be in-depth on understanding human de novo gene emergence from an environmental perspective as well as understanding species divergence from a gene emergence perspective.

Anogenital scent-marking signals fertility in a captive female Alaotran gentle lemur

The Lake Alaotra gentle lemur (Hapalemur alaotrensis) is one of the 25 most endangered primates in the world and shows low success rate in captive breeding programmes. It is therefore vital to further understand its reproductive biology. We studied a captive troop consisting of five individuals hosted at Jersey Zoo during breeding and non-breeding periods over 1 year. We collected behavioural data (n = 318 h) using all occurrence of some behaviours and ad libitum sampling methods, as well as faecal (n = 54) and anogenital scent (n = 35) samples of the breeding female. We measured sex hormone levels using enzyme immunoassay technique and investigated the volatile component of odour signals using solid-phase microextraction and gas chromatography-mass spectrometry. We observed sexual and aggressive behaviours occasionally during the breeding period. Our regression analysis showed that only period significantly predicted rates of female anogenital scent-marking, whereby the female performed anogenital scent-marking more frequently during the breeding rather than the non-breeding period. In contrast, female hormone levels did not significantly explain variation in rates of neither male nor female olfactory, sexual and affiliative behaviours, suggesting that individuals' behaviour alone is not an effective indicator of the ovulation window. The volatile chemical profile of anogenital odour secretions changed over the study, with four compounds distinguishing the fertile window during the breeding period. In conclusion, our findings suggest that anogenital scent-marking may signal the reproductive status of captive female gentle lemurs.

The effect of reproductive state on activity budget, feeding behavior, and urinary C-peptide levels in wild female Assamese macaques

Abstract

The source of maternal energy supporting reproduction (i.e., stored or incoming) is an important factor determining different breeding strategies (capital, income or mixed) in female mammals. Key periods of energy storage and allocation might induce behavioral and physiological shifts in females, and investigating their distribution throughout reproduction helps in determining vulnerable phases shaping female reproductive success. Here, we examined the effects of reproductive state on activity budget, feeding behavior, and urinary C-peptide (uCP) levels, a physiological marker of energy balance, in 43 wild female Assamese macaques (Macaca assamensis). Over a 13-month study period, we collected 96,266 instantaneous records of activity and 905 urine samples. We found that early lactating females and non-gestating–non-lactating females follow an energy-saving strategy consisting of resting more at the expense of feeding and consuming mostly fruits which contributed to enhancing their energy intake and feeding efficiency. We found an opposite pattern in gestating and late lactating females who feed more at the expense of resting and consume mostly seeds, providing a fiber-rich diet. Storing food into cheek pouches increased throughout gestation while it decreased all along with lactation. Lastly, we found the highest uCP levels during late gestation. Our results reflect different feeding adaptations in response to the energetic costs of reproduction and suggest a critical role of fat accumulation before conception and metabolizing fat during gestation and lactation. Overall, our study provides an integrative picture of the energetics of reproduction in a seasonal species and contributes to our understanding of the diversity of behavioral and physiological adaptations shaping female reproductive success.

Significance statement

To offset their substantial energetic investment in reproduction, mammalian females may modify their behavior and the way they extract energy from their environment. In addition, as a result of heightened energy expenditure, female reproduction might trigger physiological shifts. To date, most studies investigated the energetic costs of female reproduction using either a behavioral or a physiological approach. To arrive at a more comprehensive picture, we combined behavioral data with a physiological marker of energy balance, i.e., urinary C-peptide, in a seasonal primate species in its natural habitat. Our results indicate that throughout the reproductive cycle, behavioral and physiological adaptations operate concomitantly, inducing modifications in female activity budget, feeding behavior, and suggesting shifts in fat use. Overall, our results illustrate the relevance of combining data on behavior and hormones to investigate breeding strategies in coping with the energetic costs of reproduction.

The effect of data provenance on estimates of gestation length in African and Asian colobines

OBJECTIVES

It seems to be commonly accepted that gestation length within the subfamily Colobinae lasts several weeks longer in the African tribe (Colobini) than in the Asian tribe (Presbytini) even though closely related taxa of similar body mass should have similar life histories. Suspecting problems with data provenance to cause the difference, we revisited the published records expecting similar gestation lengths in both tribes if based on vetted, accurate data.

MATERIALS AND METHODS

We compiled published gestation length data for Colobini and Presbytini, labeling them as "unspecified" (n = 16) if the primary reference could not be located, methods were not described, and/or conceptions, the beginning of gestation, were determined based on sporadic observations of mating. If conceptions were determined based on changing hormone levels or patterns of daily mating records, we labeled the data as "accurate" (n = 12). We analyzed the ln transformed data in a phylogenetic framework in relation to adult female body mass.

RESULTS

In the unspecified dataset, gestation length in the two tribes overlapped extensively and did not differ significantly. However, in the accurate dataset, gestation length was significantly shorter in Colobini (not longer, as previously assumed).

DISCUSSION

Data provenance had a strong impact on the comparison, reversing the relationship in gestation length in the two sister tribes. It remains to be determined why gestation lengths differ, whether, relative to the other primates, Colobini have a shortened gestation or Presbytini a lengthened gestation, and whether similar differences exist in other closely related taxa. Addressing these questions will require additional, broader, comparative analyses.

Energetics at the urban edge: Environmental and individual predictors of urinary C-peptide levels in wild chacma baboons (Papio ursinus)

As human-modified landscapes encroach into natural habitats, wildlife face a reduction in natural food sources but also gain access to calorie-rich, human-derived foods. However, research into the energetics of wildlife living within and adjacent to urban and rural landscapes is lacking. C-peptide - a proxy for insulin production and a diagnostic tool for assessing pancreatic function in humans and domestic animals - can be quantified non-invasively from urine (uCP) and may provide a way to investigate the energetic correlates of living in human-altered landscapes. UCP is increasingly used in studies of primate energetics, and here we examine predictors of variation in uCP levels in n = 17 wild chacma baboons (Papio ursinus) living at the urban edge on the Cape Peninsula, South Africa. We find that uCP was positively associated with food provisioning and negatively with night fasting. UCP levels were comparable between winter and summer but significantly lower during spring, possibly driven by consumption of energy-rich seeds during summer and more human-derived foods during winter. UCP was elevated in pregnant females and similar for lactating and cycling females. We find no effect of dominance rank on uCP. Samples collected with synthetic Salivettes had significantly lower uCP levels than directly pipetted samples. Overall, our results indicate that uCP is a reliable, non-invasive measure of energy balance and intake in baboons, and suggest potential energetic benefits of living at the urban edge. More broadly, studies of uCP may offer unique insight into the environmental control of hormone-behaviour relationships in species crossing natural and urban environments.

The costs of competition: injury patterns in 2 Asian colobine monkeys

Aggression rarely escalates to physical conflict because doing so puts individuals at risk of injury. Escalation only pays off when the potential benefits outweigh the potential costs, that is, when resources critical to fitness are at stake. Here, we investigated the occurrence of injury in 2 Asian colobine species: Nepal gray langurs (Semnopithecus schistaceus) and Phayre’s leaf monkeys (Trachypithecus phayrei crepusculus). In both species, younger individuals are higher-ranking and might have greater incentive to fight. However, Nepal gray langurs have a strict breeding season, which may magnify male mating competition, and Phayre’s leaf monkeys, unlike Nepal gray langurs, have female-biased dispersal, which may increase female injury risk during subadulthood. Using long-term data on observed injuries (Nepal gray langurs: n = 208; Phayre’s leaf monkeys: n = 225), we modeled the monthly occurrence of injury (Y/N) and found that males received more injuries than females in both species. Also, subadults generally experienced frequent injury, as young individuals likely face challenges when competing for group membership and/or establishing rank. In Nepal gray langurs, males received 3 times more injuries during the mating season, suggesting strong competition for mates during this period, and females experienced more injuries before conception, suggesting competition to meet the nutritional requirements for reproduction. Unexpectedly, females in smaller groups received more injuries in Nepal gray langurs. Overall, these results indicate that injuries are most likely when fighting may aid in establishing group membership, achieving high rank, and reproducing. Future research should investigate the influence of injuries on fitness outcomes.

Monitoring menstrual cycle, gestation and lactation by measuring urinary oestradiol and progesterone in the captive golden snub-nosed monkey (Rhinopithecus roxellanae)

The golden snub-nosed monkey is an endangered species and study of its reproductive physiology is crucial for the species' breeding programs. Urine samples (770) from 5 mature female golden snub-nosed monkeys were collected in the Shengnongjia Nature Reserve between October 2013 and December 2014 to monitor their menstrual cycle, gestation, and lactation. The concentrations of oestradiol (E₂) and progesterone (P₄) in the samples were measured by Chemiluminescent Microparticle Immunoassay (CMIA), and the hormone concentrations were indexed to creatinine levels to compensate for differences in water content. The results showed that the E₂ and P₄ levels during the breeding season were significantly higher than those during the non-breeding season (P<0.01). The length of the menstrual cycle during the breeding season was 24.29±0.71days (mean±SEM) with a follicular cycle of 8.33±0.62days and luteal cycle of 15.27±0.83days. In addition, the levels of E₂ and P₄ began to rise on day 14 and day 10 after conception and remained at a high level until parturition. However, the E₂ and P₄ levels during lactation were lower than those during gestation (P<0.01). In summary, this study extends our knowledge regarding the basic reproductive physiology of golden snub-nosed monkeys, which could play an important role in the expansion of this species' population.

An examination of factors potentially influencing birth distributions in golden snub-nosed monkeys (Rhinopithecus roxellana)

Many species of primates are considered seasonal breeders, but the set of factors, such as food availability, day length and temperature, that influence the timing of reproductive events for both wild and captive individuals remains unclear. Here, we examine the role of factors in shaping breeding patterns in Rhinopithecus roxellana, a temperate colobine primate. We used circular statistics to describe and compare the patterns of reproductive seasonality among individuals in 13 captive groups and two free ranging but provisioned groups at various locations throughout China. Almost 90% of births occurred in March, April and May in adult females residing in both free ranging (n = 131) and captive groups (n = 407). Births occurred principally in 2-4 months prior to the peak of food availability, while conceptions occurred in 1-2 months after the peak of food availability in free ranging but provisioned groups. Day length (latitude) had a significant effect on the timing of reproduction. However, females that experienced a wide variation of temperature between the lowest and highest monthly average temperature had a later conception date. These results support that day length and temperature might be factor influencing the timing of reproductive activity.

Puberty, ovarian cycle, pregnancy, and postpartum ovulation in captive Sichuan golden monkeys (Rhinopithecus roxellana) based on changes in urinary and fecal gonadal steroid metabolites

The purpose of this study was to evaluate the reproductive status and clarify the reproductive physiology of captive Sichuan golden monkeys. The concentrations of urinary estradiol-3-glucuronide (E₂G) and pregnanediol-glucuronide (PdG) or fecal estradiol-17β (E₂) and PdG in two females, and fecal testosterone concentrations in a male, were measured continuously using enzyme immunoassays. On the basis of these hormone profiles, the follicular phase, luteal phase, and ovarian cycle were calculated to be 14.7 ± 4.8, 10.4 ± 2.8, and 25.1 ± 3.3 days, respectively. The first ovulation (puberty) in a female monkey was observed at 5.1 years old, and the first pregnancy was diagnosed at 6.4 years old. For the first 2 months of pregnancy (204 days), fecal E₂ and PdG maintained constant high values and then increased until parturition. These profiles were similar to urinary E₂G and PdG changes. During the last trimester of a twin pregnancy, fecal PdG was up to approximately three times higher compared with a single pregnancy. Therefore, fecal PdG levels in late pregnancy may be effective for the detection of a twin pregnancy. The first postpartum ovulation occurred 66 (fetal death and artificial rearing), 143 (fetal death), and 189 (natural suckling) days after parturition. The anovulation period of the natural suckling case was longer than the others. Conception and postpartum ovulation were detected between September and January. Fecal testosterone levels of the male were correlated with the fecal E₂ level of the nonpregnancy period in exhibited together female. Our results reported that urinary (E₂G and PdG) and fecal (E₂ and PdG) hormone measurement is effective for monitoring the reproductive status, thereby expanding knowledge of the reproductive endocrinology of this endangered species.

Hormonal correlates of life history characteristics in wild female Colobus vellerosus

Documenting primate life history characteristics is important because it provides information about traits that affect the timing and rate of reproduction in these long-lived species. This study describes the hormonal correlates of female reproductive events and quantifies for the first time key life history variables for Colobus vellerosus, using hormonal and observational data. This study also biologically validates that the reproductive events determined in the hormone profiles correspond to observed reproductive events for each female. We collected behavioural data on 18 females in our four study groups during 12 months (May 2012-2013) at the Boabeng-Fiema Monkey Sanctuary, using 10-min continuous focal and ad libitum sampling. We concurrently collected faecal samples (n = 1866) every 2-3 days from these 18 females (prepubescent n = 2, cycling n = 2, lactating n = 12, pregnant, n = 7, and post-reproductive n = 1) and extracted oestrogen (E2) and progesterone (P) metabolites in the field using solid-phase extraction cartridges. We created a hormone profile for each female by analyzing 1586 of our samples for E2 using radio-immuno assays, and P using enzyme-immunoassays at the Wisconsin National Primate Research Center. Mean ovarian cycle length was 24 days ± 1 (n = 2 cycles). Mean gestation length was 23 weeks (range = 21-25 weeks, n = 2 complete pregnancies). For females whose infants survived to nutritional independence, the mean inter-birth interval (IBI) was significantly longer than for females whose infants died prior to reaching nutritional independence (Mann-Whitney U Test; U = 14.5, p = 0.006; IBI surviving infants: 17.75 months, range = 8-20.75 months, n = 11 vs. IBI infant death: 11.89 months, range = 8-18.5 months, n = 9). The values for most life history traits reported in this study are similar to those documented in other similarly sized colobine species. Some values are on the lower end of the range for similarly sized colobines; C. vellerosus shows a cycle of 24 days and gestation length of 5.75 months vs. a range of 24-29 days for cycle length and 5.25-7.5 months for gestation length in other colobines. This may be due to C. vellerosus' smaller body size, or their limited access to higher quality food resources.

Assessing adaptability and reactive scope: Introducing a new measure and illustrating its use through a case study of environmental stress in forest-living baboons

In order to maintain regulatory processes, animals are expected to be adapted to the range of environmental stressors usually encountered in their environmental niche. The available capacity of their stress responses is termed their reactive scope, which is utilised to a greater or lesser extent to deal with different stressors. Typically, non-invasive hormone assessment is used to measure the physiological stress responses of wild animals, but, for methodological reasons, such measurements are not directly comparable across studies, limiting interpretation. To overcome this constraint, we propose a new measure of the relative strength of stress responses, 'demonstrated reactive scope', and illustrate its use in a study of ecological correlates (climate, food availability) of faecal glucocorticoid (fGC) levels in two forest-living troops of baboons. Results suggest the wild-feeding troop experiences both thermoregulatory and nutritional stress, while the crop-raiding troop experiences only thermoregulatory stress. This difference, together with the crop-raiding troop's lower overall physiological stress levels and lower demonstrated fGC reactive scope, may reflect nutritional stress-buffering in this troop. The relatively high demonstrated fGC reactive scope levels of both troops compared with other baboons and primate species, may reflect their extreme habitat, on the edge of the geographic range for baboons. Demonstrated reactive scope provides a means of gauging the relative strengths of stress responses of individuals, populations, or species under different conditions, enhancing the interpretive capacity of non-invasive studies of stress hormone levels in wild populations, e.g. in terms of animals' adaptive flexibility, the magnitude of their response to anthropogenic change, or the severity of impact of environmental conditions.

Influence of diet and stress on reproductive hormones in Nigerian olive baboons

A female mammal's reproductive function and output are limited by the energy she is able to extract from her environment. Previous studies of the interrelationships between energetic circumstances and reproductive function in a variety of mammal species have produced varied results, which do not all support the common assumption that higher female reproductive hormone levels, specifically progesterone, indicate better ovarian function and greater reproductive potential, and are associated with lower energetic stress. In the present study faecal progesterone and glucocorticoid levels were assessed in two troops of olive baboons (Papio anubis) in the same population. They face similar ecological challenges, except that one troop crop-raids, potentially affecting its energetic intake and stress levels. The energy intake of individual females was assessed by combining detailed feeding observations with nutritional analysis of food samples. The crop-raiding troop experienced 50% higher energy intake rates and 50% lower glucocorticoid levels compared to the non-crop-raiding troop alongside substantially lower progesterone levels. This suggests that energetic stress is associated with elevated progesterone levels and may be the cause of the non-crop-raiding troop's lower reproductive output. By comparing groups which differ little, except in terms of food access, and also by directly assessing energy intake, our study addresses some of the design limitations of previous research investigating variation in progesterone levels and energetic stress. It therefore has the potential to contribute to greater understanding of the factors affecting differences in reproductive and stress hormone levels and reproductive function in mammals experiencing different energetic circumstances.

Beware of primate life history data: a plea for data standards and a repository

Life history variables such as the age at first reproduction and the interval between consecutive births are measures of investment in growth and reproduction in a particular population or species. As such they allow for meaningful comparisons of the speed of growth and reproduction between species and between larger taxa. Especially in primates such life history research has far reaching implications and has led for instance to the "grandmother hypothesis". Other links have been proposed with respect to dietary adaptations: Because protein is essential for growth and one of the primary sources of protein, leaves, occurs much less seasonally than fruits, it has been predicted that folivorous primates should grow faster compared to frugivorous ones. However, when comparing folivorous Asian colobines with frugivorous Asian macaques we recently documented a longer, instead of a shorter gestation length in folivores while age at first reproduction and interbirth interval did not differ. This supports earlier findings for Malagasy lemurs in which all life history variables tested were significantly longer in folivores compared to frugivores. Wondering why these trends were not apparent sooner, we tried to reconstruct our results for Asian primates with data from four popular life history compilations. However, this attempt failed; even the basic, allometric relationship with adult female body mass that is typical for life history variables could not be recovered. This negative result hints at severe problems with data quality. Here we show that data quality can be improved significantly by standardizing the variables and by controlling for factors such as nutritional conditions or infant mortality. Ideally, in the future, revised primate life history data should be collated in a central database accessible to everybody. In the long run such an initiative should be expanded to include all mammalian species.

Concealed fertility and extended female sexuality in a non-human primate (Macaca assamensis)

In numerous primates living in mixed-sex groups, females display probabilistic cues of fertility to simultaneously concentrate paternity to dominant males while diluting it amongst others as a means to reduce the risk of infanticide and to increase male care for offspring. A few species, however, lack these cues and potentially conceal fertility from males; yet, to date, little is known about mating patterns and their underlying proximate mechanisms in such species. Here, we investigated mating activity and sexual consortships relative to female reproductive state in wild Assamese macaques (Macaca assamensis), a species where females lack prominent anogenital swellings and copulation calls. During two mating seasons (2837 contact hours) we recorded sexual and social behaviors, sexual consortships, and collected 1178 fecal samples (n = 15 females) which were analyzed for progestogen concentrations to assess female reproductive state and to determine the timing of ovulation and conception. Although mostly conceiving in their first ovarian cycle, females were sexually receptive throughout the entire 4-month mating season, and within-cycle mating frequencies were not increased during fertile phases. Dominant males did not monopolize fertile matings, and consortships by high-ranking males lasted for long periods, which were not exclusively linked to female fertile phases. Furthermore, females copulated promiscuously but not randomly, i.e. for almost every female, matings were concentrated to a certain male, irrespective of male rank. Collectively, we demonstrate that fertility is undisclosed to males. The extreme extended female sexuality facilitated by concealed fertility may allow females to create differentiated mating relationships within a promiscuous mating system. Our study provides important new insight into the plasticity of female sexuality in non-human primates.

Estrogen and Progestogen Correlates of the Structure of Female Copulation Calls in Semi-Free-Ranging Barbary Macaques (Macaca sylvanus)

Females of many Old World primates produce conspicuous vocalizations in combination with copulations. Indirect evidence exists that in Barbary macaques (Macaca sylvanus), the structure of these copulation calls is related to changes in reproductive hormone levels. However, the structure of these calls does not vary significantly around the timing of ovulation when estrogen and progestogen levels show marked changes. We here aimed to clarify this paradox by investigating how the steroid hormones estrogen and progesterone are related to changes in the acoustic structure of copulation calls. We collected data on semi-free-ranging Barbary macaques in Gibraltar and at La Forêt des Singes in Rocamadour, France. We determined estrogen and progestogen concentrations from fecal samples and combined them with a fine-grained structural analysis of female copulation calls (N = 775 calls of 11 females). Our analysis indicates a time lag of 3 d between changes in fecal hormone levels, adjusted for the excretion lag time, and in the acoustic structure of copulation calls. Specifically, we found that estrogen increased the duration and frequency of the calls, whereas progestogen had an antagonistic effect. Importantly, however, variation in acoustic variables did not track short-term changes such as the peak in estrogen occurring around the timing of ovulation. Taken together, our results help to explain why female Barbary macaque copulation calls are related to changes in hormone levels but fail to indicate the fertile phase.

Reproductive characteristics of wild female Phayre's leaf monkeys

Understanding female reproductive characteristics is important for assessing fertility, interpreting female behavior, and designing appropriate conservation and captive management plans. In primate species lacking morphological signs of receptivity, such as most colobines, determination of reproductive parameters depends on the analysis of reproductive hormones. Here, we use fecal hormone analysis to characterize cycle patterns (N=6 females) and gestation length (N=7 females) in a group of wild Phayre's leaf monkeys (Trachypithecus phayrei crepusculus) in Phu Khieo Wildlife Sanctuary, Thailand. We found that both fecal estrogen (fE) and progestin (fP) levels showed clear biological patterns indicative of ovulation and conception. However, because fP patterns were inadequate in determining the end of the luteal phase, we used fE rather than fP patterns to delineate menstrual cycle parameters. We found a mean cycle length of 28.4 days (N=10), with follicular and luteal phases of 15.4 (N=10) and 12.5 days (N=14), respectively. On average, females underwent 3.57 (N=7) cycles until conception. Average gestation length was 205.3 days (N=7), with fE levels increasing over the course of pregnancy. Overall, the reproductive characteristics found for Phayre's leaf monkeys were consistent with results for other colobine species, suggesting that fecal hormone monitoring, particularly for fE metabolites, can provide useful reproductive information for this species.

Phytochemicals and reproductive function in wild female Phayre's leaf monkeys (Trachypithecus phayrei crepusculus)

Female reproduction is known to be influenced by food availability and its impact on energetic status. However, emerging evidence suggests that the phytochemical content of food may also be an important factor. Here, we investigated this hypothesis, presenting 20 months of data on fecal progestin (fP) patterns in wild female Phayre's leaf monkeys (Trachypithecus phayrei crepusculus). We examined whether (a) the availability of Vitex (a plant known to contain phytochemicals) might be linked to seasonal fP levels, (b) fP levels were associated with female reproductive performance, and (c) reproductive performance might also be linked with energetic status (as measured by physical condition). We collected fecal samples (N=2077) from 10 adult females to analyze estrogen (fE) and progestin (fP) metabolites, behavioral data from 7 cycling females to determine receptivity, and monthly data on Vitex availability and female physical condition. Seasonally elevated fP levels were found in all females, with higher levels when Vitex leaves and fruits were abundant. During the period of high progestins, females had longer cycle lengths and follicular phases, while receptive periods did not change. Nevertheless, when ovulations occurred, females were more likely to conceive. On the other hand, conceptions were also more likely when physical condition was improving, suggesting that the effects of phytochemicals and energetic status on reproduction may be difficult to separate. Although our results support the predicted effects of Vitex on endocrine and reproductive function, future studies with detailed feeding data and chemical analyses of plants are needed to confirm this finding.

Non-invasive methods for estradiol recovery from infant fecal samples

While the activation of the infant hypothalamic-pituitary-gonadal axis and the existence of a postnatal gonadotropin surge were first documented in the early 1970s, study of the longitudinal development of gonadal hormones in infancy, and the potential physiological and behavioral correlates of this development, have been hampered by reliance on infrequent serum sampling. The present study reports the validation of a non-invasive method for repeated assessment of steroid hormones in infant fecal samples. Fecal samples were collected in and excised from cotton diaper liners and extracted using methanol. Extracts were analyzed for estradiol using a diluted assay modification. Method validity was supported by a steroid recovery rate of at least 80%, a sensitivity of 0.35 pg/ml, and inter- and intra-assay coefficients of variations of less than 10 and 20%, respectively. Variation in estradiol concentration was assessed across (1) sample type (scraped vs. cut from diaper liner), (2) time of day (morning vs. afternoon/evening samples), (3) time interval between samples, and (4) time-to-assay (1 day vs. 489 days after collection). Of these characteristics, only the time interval between samples within an individual was significantly associated with estradiol concentration. This is the first report of human infant fecal estradiol levels. The results support fecal recovery as a novel and powerful non-invasive tool for longitudinal studies of human infants, expanding research opportunities for investigating development of sex-specific behaviors in infancy, and the potential effects of endocrine disruptors on development.

Reproductive and Life History Parameters of Wild Female Macaca assamensis

Information on basic reproductive parameters and life-history traits is crucial for the understanding of primate evolution, ecology, social behavior, and reproductive strategies. Here, we report 4 yr of data on reproductive and life-history traits for wild female Assamese macaques (Macaca assamensis) at Phu Khieo Wildlife Sanctuary, northeastern Thailand. During 2 consecutive reproductive seasons, we investigated reproductive behavior and sexual swelling size in 16 females and collected 1832 fecal samples. Using enzyme immunoassays, we measured fecal estrogen and progesterone metabolites to assess ovarian activity and timing of ovulation and to ascertain conceptions and pregnancies. Timing of reproduction was strictly seasonal (births: April-July, 86% in April-June, 4 yr, n = 29; conceptions: October-February, 65% in December-January, 2 yr, n = 17). Females showed no cyclic ovarian activity outside the mating season and conceived in their first or second cycle (mean: 1.2 cycles to conception, n = 13). Gestation length was on average 164.2 d (range: 158-170, n = 10), and females had their first infant at an age of 5 yr (n = 4). Interbirth intervals were bimodally distributed, with females giving birth on average every 13.9 or 23.2 mo. Shorter interbirth intervals were linked to early parturition within the birth season. Most females displayed subcaudal sexual swellings which, however, did not reliably indicate female reproductive status or fertility. Overall, our results fall within the range of findings reported for other macaque species. These results thus add to the growing body of information available for wild macaques, facilitating comparative studies for a better understanding of interspecific differences in social and reproductive patterns.

Age-dependent changes in fecal 17beta-estradiol and progesterone concentrations in female spider monkeys (Ateles geoffroyi)

The objective of this study was to investigate whether sex steroids decreased with age in female black-handed spider monkeys (Ateles geoffroyi). Fecal concentrations of 17beta-estradiol and progesterone (five samples/wk) and the number of ovulatory and anovulatory cycles were compared between adult (n=3) and aged females (n=2). All animals (regardless of age) had higher 17beta-estradiol concentrations during the fertile than the nonfertile phases. However, during the fertile phase, concentrations of this hormone were significantly higher in adult females. Conversely, progesterone concentrations varied normally throughout the menstrual cycle in both adult and aged animals, with no significant difference between age classes. Similarly, there was no significant effect of age on the number of ovulatory and anovulatory cycles. In conclusion, we inferred that the aged female spider monkeys did not reach menopause, instead they remained in a perimenopausal period characterized by changes in fecal concentrations of ovarian steroids and hypothalamus-hypophysis-ovary axis activity, as well as irregular menstrual flows, for prolonged intervals.

Rates of self-directed behaviour and faecal glucocorticoid levels are not correlated in female wild olive baboons (Papio hamadryas anubis)

Non-invasive methods to quantify components of stress in non-human animals rely typically on the use of physiological or behavioural measures. At the physiological level, stress is usually measured non-invasively in terms of faecal or urinary glucocorticoid output. A common group of behavioural measures used are self-directed behaviours (SDBs), which have been shown to be linked to anxiety, a subset of stress, although a number of authors have explicitly linked SDBs to stress more generally. Whether increased rates of SDBs are likely to be associated with increased faecal glucocorticoid ouput in wild mammals remains unclear. Here, for wild female olive baboons, we show no association between day-to-day changes in levels of SDB and cortisol metabolite excretion. We also show no relationship between long-term mean levels of these variables. We discuss several possible interpretations of our results, including the possibility that SDBs represent a behavioural coping mechanism, helping to ameliorate the physiological stress response.

Individual Facial Coloration in Male Eulemur fulvus rufus: A Condition-dependent Ornament?

Researchers studying individual variation in conspicuous skin coloration in primates have suggested that color indicates male quality. Although primate fur color can also be flamboyant, the potential condition dependence and thus signaling function of fur remains poorly studied. We studied sources of variation in sexually dichromatic facial hair coloration in red-fronted lemurs (Eulemur fulvus rufus). We collected data on 13 adult males in Kirindy Forest, Madagascar, during two study periods in 2006 and 2007, to determine whether variation in facial hair coloration correlates with male age, rank, androgen status, and reproductive success. We quantified facial hair coloration via standardized digital photographs of each male, assessed androgen status using fecal hormone measurements, and obtained data on reproductive success through genetic paternity analyses. Male facial hair coloration showed high individual variation, and baseline coloration was related to individual androgen status but not to any other parameter tested. Color did not reflect rapid androgen changes during the mating season. However, pronounced long-term changes in androgen levels between years were accompanied by changes in facial hair coloration. Our data suggest that facial hair coloration in red-fronted lemur males is under proximate control of androgens and may provide some information about male quality, but it does not correlate with dominance rank or male reproductive success.

Signals of female reproductive quality and fertility in colony-living baboons (Papio h. anubis) in relation to ensuring paternal investment

The fitness of a female's offspring depends cruicially on the traits, genetic and paternal, that the father contributes. As such, females may either have an interest in behaviorally choosing the highest-quality male, or in reliably signaling their fertility status to males. Combining hormonal data on a female's ovulatory fertile window with a behavioral context, we suggest that captive female olive baboons (Papio h. anubis) provide fathers with reliable signals of their fertile period. One signal, the maximum anogenital swelling (AGA), typically coincided with a 4-day fertile window of ovulation, which occurred 2-3 days prior to deturgescence. As expected from previous studies, AGA swelling indicated general attractiveness to males, and males attended to the relative attractiveness of females. Males approached and copulated with females significantly more often during the 4-day window around ovulation, irrespective of the absolute swelling stage. The two adult males present in the group were both able to copulate with consistent partners as at least two cycling females were available in most months; the dominant male was more selective about the timing of his copulations close to ovulation during the maximal swelling phase. Females with ovulatory but nonconceptive cycles were less attractive to males, especially during their maximal AGA swelling phase.

Seasonal and social influences on fecal androgen and glucocorticoid excretion in wild male long-tailed macaques (Macaca fascicularis)

Whereas it is well known that in strictly seasonal breeding primates (income breeders), alike other vertebrates, males show pronounced changes in testicular and adrenal hormone levels concurrent with reproductive activity, hormonal patterns in males of non-strictly seasonal breeding primate species (capital breeders) and their relation to seasonal and social correlates remain largely unknown. In the present study, we examined the annual pattern of fecal androgen and glucocorticoid excretion and their relationship to environmental (rainfall, temperature) and social factors (number of cycling females, male aggression and copulation rates, male dominance rank) in a group of wild long-tailed macaques (Macaca fascicularis), a species with a moderate degree of reproductive seasonality and classified as capital breeder. The study was carried out in the Gunung Leuser National Park, North Sumatra, Indonesia over a period of ten months encompassing the conception and the birth season. Our results show that male long-tailed macaques exhibit a distinct annual variation in both androgen and glucocorticoid levels. Androgen (but not glucocorticoid) levels were significantly elevated during the conception period in association with elevated rates of male-male aggression and copulatory activity, both strongly related to the number of cycling females in the group. Neither glucocorticoid nor androgen levels were related to male dominance rank or to the environmental parameters investigated. Interestingly, levels of both hormones started to increase in the late birth season and thus 1-2 months prior to the mating season, suggesting that male long-tailed macaques go through pre-breeding hormonal changes in preparation for prospective challenges. Our data thus provide the first evidence that males of a non-strictly seasonal breeding species/capital breeder show endocrine patterns generally similar to those found in strictly seasonal/income breeders.

Female reproductive signaling, and male mating behavior, in the olive baboon

Baboon sexual swellings are among the largest and most colorful signals displayed by any mammal, and many baboon studies have shown an association between sexual swellings and both female and male sexual behavior. However, the extent to which female behavior and sexual swellings combine to signal the timing of ovulation and the fertile period to males, and the extent to which males use these and other signals when determining patterns of mating behavior, remain key topics of research. Here we assess the social and sexual behavior of both female and male olive baboons with respect to detailed measures of swelling size made from digital photographs, measures of fecal progestogen and estrogen levels, and estimates of the timing of ovulation and the fertile period based on those levels. Female aggression and grooming behavior were unrelated to fecal progestogen and estrogen levels, but there were some significant relationships between these hormonal measures and presenting behaviors. Measures of female behavior collected during the study did not appear to reveal the timing of ovulation or the fertile period. Male consortship behavior was closely tied to fine-scale changes in sexual swelling size, but copulation behavior was not. Copulation behavior of consorting males was, however, linked to the timing of both ovulation and the fertile period, suggesting that males did have knowledge about these timings. Together these results suggest that males used fine-scale swelling size changes when deciding when to consort, but that consorting males did not use fine-scale swelling size changes in deciding when to copulate. We propose that swelling size may advertise the period during which males should consort with females, with other signals available only from closer inspection then used by consorting males to assess the timing of the fertile period more accurately. An important implication of this interpretation is that different males may have access to different signals of ovulation at any one time. Such a system would allow females to offer different males different information simultaneously, perhaps offering a solution to the 'female dilemma' of how females can simultaneously assure and confuse paternity in multi-male societies.

Seasonality of mating and birth in wild black-and-white snub-nosed monkeys (Rhinopithecus bieti) at Xiaochangdu, Tibet

Data on mating and birth seasonality were recorded in wild black-and-white snub-nosed monkeys (Rhinopithecus bieti) at Xiaochangdu in the Honglaxueshan National Nature Reserve, Tibet. This represents one of the harshest habitats utilized by any nonhuman primate. Variation in food availability, temperature, and photoperiod were examined to identify ecological influences on the timing of reproductive events. Mating was observed to occur mostly between July and October and to coincide with peak food availability and temperature, while births occurred between February and mid-March, the end of the period of lowest food availability. This pattern may be an adjustment to the extreme environmental conditions characteristic of this field site.

The timing of ovulation with respect to sexual swelling detumescence in wild olive baboons

Baboon researchers commonly use the timing of sexual swelling detumescence to infer the timing of ovulation. These estimates are then used for a variety of purposes, including the interpretation of male and female behaviour, assessment of likely paternity, and the calculation of gestation lengths. Although captive studies have measured the timing of ovulation with respect to detumescence, this has not been measured in wild baboons. Here, we use observational data on female sexual swellings, and hormonal data measured from faeces, to investigate the timing of ovulation with respect to detumescence in wild olive baboons. Our data show similar variability in the timing of ovulation with respect to detumescence as that produced by captive studies, although there are some notable differences, including the absence of any ovulations measured on or after the day of swelling detumescence. We discuss the importance of our results for baboon researchers using swellings to infer ovulation as part of their studies.

Female Barbary macaque (Macaca sylvanus) copulation calls do not reveal the fertile phase but influence mating outcome

In a number of primate species, females utter loud and distinctive calls during mating. Here we aim to clarify the information content and function of Barbary macaque (Macaca sylvanus) copulation calls by testing (i) whether or not copulation calls advertise the female fertile phase and (ii) whether and how copulation calls influence male ejaculatory behaviour. In order to do this, we combined hormone measurements with acoustic analysis and behavioural observations. In contrast to a previous study implying that the structure of copulation calls indicates the timing of the fertile phase, our results, using objective endocrine criteria for assessing ovulation, provide evidence that the structure of copulation calls of female Barbary macaques does not reveal the timing of the fertile phase. More importantly, females seem to influence the likelihood of ejaculation by calling versus remaining silent and by adjusting the timing of call onset. Females make use of this ability to influence mating outcome to ensure ejaculatory matings with almost all males in the group. In addition, calls given during ejaculatory copulations differ from those during non-ejaculatory copulations, providing information about mating outcome for listeners. We conclude that in this species, copulation calls apparently serve to enhance sperm competition and maximize paternity confusion.

Baboon sexual swellings: information content of size and color

Primate sexual swellings are hormone-dependent sexual signals that play a key role in determining patterns of behavior. They are among the most conspicuous signals exhibited by any mammal, and their large size and bright coloration have fascinated evolutionary biologists for well over a century. A number of different adaptive hypotheses have been proposed for the evolution of sexual swellings, and there have been several recent attempts to test some of these using precise swelling measurements made in the field. Most of these studies have focused only on the size element of the swelling, and those that have measured other aspects of swellings, such as color, have done so only crudely. A focus solely on swelling size is inconsistent with most theoretical models of mate choice, which emphasize the importance of multiple cues within sexual signals. Here, we present data on baboon (Papio hamadryas anubis) sexual swellings, including measures of both swelling size and color, measured objectively using digital photography at Gashaka-Gumti National Park, Nigeria. We combined these measurements with detailed data on fecal progestogen and estrogen levels, and estimates of the timing of ovulation and the fertile period around ovulation based on those levels. We show that swelling color and size vary independently, and that, consistent with results in other species, swelling size contains information about the timing of ovulation and the fertile period. However, we show that swelling color does not contain such information. In addition, swelling size contains information about female parity, and we found some evidence to suggest that color may also contain such information. These results indicate that baboon sexual swellings may contain information about multiple aspects of female fertility. We discuss the implications of these results for understanding the nature of swellings as behavioral signals, and the role of swellings in mate choice.

Female ovarian cycle phase affects the timing of male sexual activity in free-ranging Barbary macaques (Macaca sylvanus) of Gibraltar

Although all macaques have a multimale multifemale mating system, the degree of promiscuity shown by the Barbary macaque is considered to be extreme in terms of both mating frequency and number of mating partners. How mating activity is distributed throughout the female menstrual cycle and whether or not copulations are concentrated around the fertile phase as in other members of the genus is, however, not known. To examine this, we collected data on rates of copulation throughout 29 ovarian cycles from 13 free-ranging females of the Gibraltar Barbary macaque population and related them to the time of ovulation and the female fertile phase as determined from fecal hormone analysis. In addition, patterns of male inspection of females and time spent in consortship, both indicators of female attractivity, were also analyzed. The results indicate that both mating behavior and female attractivity vary predictably with ovarian cycle stage. Rates of copulation were found to increase toward the time of ovulation, with a distinct peak of ejaculatory (but not non-ejaculatory) copulations occurring in the fertile phase. Additionally, we show that frequency of inspection of females by males and time spent in consortship were also highest during the fertile phase and that ejaculatory copulations and male pericopulatory behaviors were significantly correlated with levels of female sex hormones. Our findings indicate that the Barbary macaque shows a mating pattern during the cycle similar to that described for other members of the genus. More importantly, however, our study provides clear evidence that despite an extreme degree of promiscuity Barbary macaque males concentrate their reproductive effort to the fertile phase, implying that they are able to discern this period and that thus timing of ovulation is not concealed from them. Estrogen-related cues appear to be involved in the process of recognition of female reproductive status by males, but the exact nature of these cues and how male Barbary macaques use them remains to be clarified.

Grooming in Barbary macaques: better to give than to receive?

It is well established that grooming underpins sociality in group-living primates, and a number of studies have documented the stress-reducing effects of being groomed. In this study, we quantified grooming behaviour and physiological stress (assessed by faecal glucocorticoid analysis) in free-ranging Barbary macaques, Macaca sylvanus. Our results indicate that it is the giving rather than the receiving of grooming that is associated with lower stress levels. These findings shed important new light on the benefits of this key behaviour in primate social life.

Life history costs and benefits of encephalization: a comparative test using data from long-term studies of primates in the wild

The correlation between brain size and life history has been investigated in many previous studies, and several viable explanations have been proposed. However, the results of these studies are often at odds, causing uncertainties about whether these two character complexes underwent correlated evolution. These disparities could arise from the mixture of wild and captive values in the datasets, potentially obscuring real relationships, and from differences in the methods of controlling for phylogenetic non independence of species values. This paper seeks to resolve these difficulties by (1) proposing an overarching hypothesis that encompasses many of the previously proposed hypotheses, and (2) testing the predictions of this hypothesis using rigorously compiled data and utilizing multiple methods of analysis. We hypothesize that the adaptive benefit of increased encephalization is an increase in reproductive lifespan or efficiency, which must be sufficient to outweigh the costs due to growing and maturing the larger brain. These costs and benefits are directly reflected in the length of life history stages. We tested this hypothesis on a wide range of primate species. Our results demonstrate that encephalization is significantly correlated with prolongation of all stages of developmental life history except the lactational period, and is significantly correlated with an extension of the reproductive lifespan. These results support the contention that the link between brain size and life history is caused by a balance between the costs of growing a brain and the survival benefits the brain provides. Thus, our results suggest that the evolution of prolonged life history during human evolution is caused by increased encephalization.

Female sexual behavior and sexual swelling size as potential cues for males to discern the female fertile phase in free-ranging Barbary macaques (Macaca sylvanus) of Gibraltar

Although female catarrhine primates show cyclic changes in sexual behavior and sexual swellings, the value of these sexual signals in providing information to males about timing of the fertile phase is largely unclear. Recently, we have shown that in Barbary macaques, males receive information from females which enables them to discern the fertile phase and to focus their reproductive effort accordingly. Here, we investigate the nature of the cues being used by examining female sexual behavior and the size of sexual swelling as potential indicators of the fertile phase. We collected behavioral data and quantified swelling size using digital images of 11 females of the Gibraltar Barbary macaque population and related the data to the time of ovulation and the fertile phase as determined from fecal hormone analysis. We found that rates of female sexual behaviors were not correlated with female estrogen levels and did not significantly differ between the fertile and non-fertile phases of the cycle. In contrast, swelling size was significantly correlated with female estrogen levels and increased predictably towards ovulation with size being maximal during the fertile phase. Moreover, frequencies of male ejaculatory copulations showed a strong positive correlation with swelling size and highest rates were found during maximum swelling. Our data provide strong evidence that female Barbary macaques honestly signal the probability of fertility through sexual swelling and that males apparently use this information to time their mating activities. Honest advertising of the fertile phase might be part of a female strategy to manipulate male mating behavior for their own advantage, such as ensure fertilization with high quality sperm or influence paternity outcome.

Reduced reproductive function in wild baboons (Papio hamadryas anubis) related to natural consumption of the African black plum (Vitex doniana)

Several authors have suggested that the consumption of plant compounds may have direct effects on wild primate reproductive biology, but no studies have presented physiological evidence of such effects. Here, for two troops of olive baboons (Papio hamadryas anubis) at Gashaka-Gumti National Park, Nigeria, we show major seasonal increases in levels of fecal progesterone metabolites in females, and provide evidence that this is linked to the consumption of natural plant compounds. Increases in fecal progestogen excretion occurred seasonally in all females, in all reproductive states, including lactation. Detailed feeding data on the study animals showed that only one food species is consumed by both troops at the time of observed progestogen peaks, and at no other times of the year: the African black plum, Vitex doniana. Laboratory tests demonstrated the presence of high concentrations of progestogen-like compounds in V. doniana. Together with published findings linking the consumption of a related Vitex species (Vitex agnus castus) to increased progestogen levels in humans, our data suggest that natural consumption of V. doniana was a likely cause of the observed increases in progestogens. Levels of progestogen excretion in the study baboons during periods of V. doniana consumption are higher than those found during pregnancy, and prevent the expression of the sexual swelling, which is associated with ovulatory activity. As consortship and copulatory activity in baboons occur almost exclusively in the presence of a sexual swelling, V. doniana appears to act on cycling females as both a physiological contraceptive (simulating pregnancy in a similar way to some forms of the human contraceptive pill) and a social contraceptive (preventing sexual swelling, thus reducing association and copulation with males). The negative effects of V. doniana on reproduction may be counter-balanced by the wide-range of medicinal properties attributed to plants in this genus. This is the first time that physiological evidence has been presented of direct effects of plant consumption on the reproductive biology of wild primates.