Reproduction in free-ranging Propithecus verreauxi: Estrus and the relationship between multiple partner matings and fertilization

Female sifaka mate selectively with one or more resident and/or non-resident males during the breeding season. Various adaptive explanations have been advanced to explain why female primates mate with multiple males including that 1) females seek to confuse paternity and thereby forestall male infanticide and/or ensure male infant care or 2) females seek to ensure fertilization. Assessing the power of fertilization insurance to explain mating patterns in females requires information on the temporal relationship between mating and ovarian hormones. The hormonal correlates of reproduction and mating in free-ranging Propithecus verreauxi were investigated using excreted steroids as indices of reproductive state. Solid-phase extraction and radioimmunoassay techniques were used to measure unconjugated estradiol (E₃) and progesterone (P₄) in 485 desiccated fecal samples collected from five female sifaka before and during the breeding season at Beza Mahafaly, Madagascar. Results suggest that behavioral estrus was characterized by 10- to 15-day elevations in E₂; hormonal activity was observed to be similar to pseudo-estrus reported for other lemur species; apparent conception was associated with sustained P₄ elevations beginning 1 to 3 days post-estrus with gestational phase elevations of E₂ beginning 42 to 45 days post-conception; and mating with multiple partners appeared not to be a prerequisite to fertilization, as conception resulted from both monoandrous and polyandrous matings. These preliminary data suggest that fertilization insurance is not adequate to explain polyandrous mating in sifaka at Beza Mahafaly. © 1996 Wiley-Liss, Inc.     

小熊猫妊娠期粪便中孕酮、雌二醇的水平变化

2000年3—8月在成都动物园和成都大熊猫繁育研究基地,用放射免疫分析法测定了6只雌性小熊猫粪样中孕酮（P）和雌二醇（E2）的水平变化,同时对其繁殖行为进行了观察。研究结果表明,交配后的雌体粪样中E2浓度下降至基础水平,P浓度在30d后上升至150ng／g以上;怀孕雌体在妊娠期粪样中P水平在200ng／g以上,P峰值可以达500ng／g以上;假妊娠者粪样中P水平一般不超过150ng／g,P峰值在200ng／g以下;雌体产前半个月孕酮迅速下降,E2缓慢上升,产后P保持在基础水平。这意味着可通过测定粪便中P水平进行早孕诊断、产期预测和真假妊娠判断。根据行为观察和粪样激素分析可知,雌兽妊娠期为123—128d（X=124,N=5）,产仔率为1．8／胎（N=5）。     

雌性小熊猫粪样中雌二醇与孕酮水平的变化与繁殖启动的关系

于1999年12月-2000年4月在成都动物园和成都大熊猫繁育研究基地,用放射免疫分析法测定了4只雌性小熊猫（Ailurus fulgens)粪样中雌二醇(E2)和孕酮(P)水平的变化,同时对其交配行为进行了观察。研究结果表明：雌性小熊猫进入发情期后,粪样中E2迅速升高,并多次出现峰值,表明小熊猫可能是季节性多发情动物。交配行为发生前E2出现峰值,P水平上升,说明E2和P是启动雌性小熊猫交配行为的重要因素;未伴随有P水平相对上升的E2峰值不能引起雌性小熊猫发生交配行为,该现象为暗发情。交配行为发生后P水平持续升高,据此推断小熊猫的排卵方式可能是诱导排卵,诱导因子是交配刺激。     

Steroid metabolism and validation of noninvasive endocrine monitoring in the African wild dog (Lycaon pictus)

The purpose of this study was to validate noninvasive endocrine monitoring techniques for African wild dogs (Lycaon pictus) and to establish physiological validity of these methods by evaluating longitudinal reproductive-endocrine profiles in captive individuals. To determine the primary excretory by-products of ovarian steroid metabolism, [¹⁴C]-progesterone and [³H]-estradiol were co-administered to a female and all excreta were collected for 80 hr postinjection. Radiolabel excretion peaked ≤ 18 hr postinfusion, and progesterone and estradiol metabolites were excreted in almost equivalent proportions in urine (39.7 and 41.1%, respectively) and feces (60.3 and 58.9%, respectively). Most of the urinary metabolites were conjugated (estradiol, 94.3 ± 0.3%; progesterone, 90.4 ± 0.5%), so that immunoassays for pregnanediol-3α-glucuronide (PdG) and estrogen conjugates (EC) were effective for assessing steroid metabolites. Two immunoreactive estrogens (estradiol and estrone) and at least one immunoreactive progesterone metabolite (3α-hydroxy-5α, pregnan-20-one) were detected in feces. Urine and fecal samples were collected (1–3 times per week) for 1.5 yr from one adult female and two adult males to assess longitudinal steroid metabolite excretion. Overall correlation of urinary PdG to matched, same-day fecal progesterone metabolites immunoreactivity was 0.38 (n = 71, P < 0.05). Similarly, urinary EC was correlated (P < 0.05) with same-day fecal estrogen immunoreactivity (r = 0.49, n = 71). During pregnancy and nonpregnant cycles, copulation occurred at the time of peak (or declining) estrogen metabolites and increasing progesterone metabolites concentrations. Estrus duration was 6–9 days and gestation lasted 69 days with parturition occurring coincident with a drop in progesterone metabolites. Males exhibited seasonal trends in fecal testosterone excretion with maximal concentrations from July to September coincident with peak mating activity. Although these limited longitudinal hormone profiles should be interpreted cautiously, noninvasive gonadal steroid monitoring suggests that: (1) both female and male wild dogs may exhibit reproductive seasonality in North America, (2) females are monoestrous, and (3) peak testicular activity occurs between August and October coincident with mating behavior. From a conservation perspective, noninvasive endocrine monitoring techniques should be useful for augmenting captive breeding programs, as well as for developing an improved understanding of the physiological mechanisms underlying reproductive suppression in response to social and ecological pressures. Zoo Biol 16:533–548, 1997. © 1997 Wiley-Liss, Inc.     

Paternity and kinship patterns in polyandrous moustached tamarins (Saguinus mystax)

We studied patterns of genetic relatedness and paternity in moustached tamarins, small Neotropical primates living in groups of 1–4 adult males and 1–4 adult females. Generally only one female per group breeds, mating with more than one male. Twin birth are the norm. In order to examine the genetic consequences of this mating pattern, DNA was extracted from fecal samples collected from two principal and six neighboring groups. DNA was characterized at twelve microsatellite loci (average: seven alleles/locus). We addressed the following questions: Do all adult males have mating access to the reproductive female of the group? How is paternity distributed across males in a group? Can polyandrous mating lead to multiple paternity? Are nonparental animals more closely related to the breeders than to the population mean? And, are mating partners unrelated? Breeding females mated with all nonrelated males. In at least one group the father of the older offspring did not sire the youngest infant although he was still resident in the group. We also found evidence for multiple paternity in a supposed twin pair. Yet, within each group the majority (67–100%) of infants had the same father, suggesting reproductive skew. Relatedness within groups was generally high (average R = 0.31), although both nonrelated males and females occurred, i.e., immigrations of both sexes are possible. Mating partners were never found to be related, hence inbreeding seems to be uncommon. The results suggest that while the social mating system is polyandry, paternity is often monopolized by a single male per group. Am J Phys Anthropol, 2005. © 2004 Wiley-Liss, Inc.     

Steroid excretion during the ovarian cycle in captive and wild muriquis,Brachyteles arachnoides

Urine, feces, and copulation frequency were collected from two captive muriqui females, Brachyteles arachnoides, at the Centro de Primatologia do Rio de Janeiro following the resumption of postpartum ovarian cycles. Fecal steroid profiles from seven wild muriqui females at the Estação Biologica de Caratinga, Minas Gerais, Brazil, were compared to the captive females to determine the approximate patterns of steroid excretion relative to the urinary LH peak. Hormonal profiles from one of the captive female muriquis revealed a discrete urinary LH peak. For this female, fecal progesterone increased on the same day as the urinary LH peak, while fecal estradiol increased 6 days later and urinary steroids increased 5 days later. For both captive females, the onset of fecal progesterone increase was preceded by the onset of copulations, which occurred during at least a 5-day period. The complete fecal hormonal profiles of the one captive female for which continuous data were available were similar to those found in wild muriqui monkeys, with the onset of an increase in sustained progesterone levels occurring several days prior to the onset of sustained estradiol increase. These patterns suggest that fecal progesterone may be excreted rapidly in this species. The onset of sustained increase in fecal progesterone levels, together with the consistent delay in the onset of the sustained increase in estradiol, may provide the best indicators of the periovulatory period for muriqui females. Am. J. Primatol. 42:311–321, 1997. © 1997 Wiley-Liss, Inc.     

Serum and fecal steroid analysis of ovulation,pregnancy, and parturition in the black rhinoceros (Diceros bicornis)

Studies were conducted to determine: (1) if fecal hormone metabolite concentrations correlated with serum estrogen and progesterone concentrations, follicular activity and reproductive behavior in the black rhinoceros (Diceros bicornis) and (2) if threshold values of respective fecal metabolite concentrations correlated with pregnancy. Blood and fecal samples were collected, in conjunction with transrectal ultrasound and behavior observations, for an 18-month period from one black rhinoceros female. Subsequently, serial fecal samples were collected from 13 females in 10 zoos. Quantitative analysis of serum progesterone (P₄) and estradiol (E₂) was performed by radioimmunoassay (RIA): analysis of fecal estrogen metabolites (E) and fecal progesterone metabolites (P) were performed by enzyme immunoassay (EIA). Serum P₂ concentrations identified two luteal phase patterns and two nadirs which corresponded with behavioral estrus. Fecal E patterns indicated a sharp peak which corresponded with breeding. concentrations of fecal P illustrated identifiable nadirs and several peaks which corresponded to serum P₄ nadirs and luteal phases. Serum P₄ concentrations were not different between the luteal phase and pregnancy. Fecal P concentrations started to rise above luteal phase concentrations approximately 150 days postbreeding and remained elevated until immediately before parturition. Serum E₂ and fecal E concentrations rose and subsequently declined after parturition. In the fecal samples from seven pregnant females, fecal P concentrations were similarly elevated compared to six nonpregnant females. Results indicated that fecal steroid metabolites accurately reflected serum steroid hormone concentrations and that the measurement of P and E concentrations permitted the characterization of the estrous cycle, the diagnosis of pregnancy, and the onset of parturition. Zoo Biol 16:121–132, 1997. © 1997 Wiley-Liss, Inc.     

Long-term fitness benefits of polyandry in a small mammal, the bank vole Clethrionomys glareolus

Polyandry, i.e. mating with multiple males within one reproductive event, is a common female mating strategy but its adaptive function is often unclear. We tested whether polyandrous females gain genetic benefits by comparing fitness traits of monandrous (mated twice with a single male) and polyandrous (mated twice with two different males) female bank voles Clethrionomys glareolus. We raised the offspring in the laboratory until adulthood and measured their body size, before releasing them to outdoor enclosures to overwinter. At the onset of the breeding season in the following spring, we found that offspring of polyandrous females performed significantly better at reproduction than those of monandrous females. This was mainly due to sons of polyandrous females producing significantly more offspring than those of monandrous females. No significant differences were found for offspring body mass or winter survival between the two treatments. Our results appear to provide evidence that bank vole females gain long-term benefits from polyandry.     

Fecal steroid hormone analysis as an indicator of reproductive function in the cheetah

Techniques were developed and validated to measure fecal estrogen and progesterone concentrations of the female cheetah. Fecal samples were collected from seven mature females. Cheetahs were monitored before mating and continued until parturition. Four females had normal pregnancies, one conceived but the pregnancy resulted in spontaneous abortion, one was mated but apparently did not conceive and one was treated with gonadotropin-releasing hormone (GnRH) and human chorionic gonadotropin (hCG) to induce follicular growth and ovulation. Vaginal superficial cells increased with increasing estrogen concentrations. Peak estrogen occurred one day postcopulation. Increases in fecal progesterone concentrations, indicative of ovulation, occurred after copulation and hormonally induced ovulation. For the first time reproductive function can be monitored in the cheetah using noninvasive sample collection. © 1994 Wiley-Liss, Inc.     

Reproductive endocrine patterns in captive female and male red wolves (Canis rufus) assessed by fecal and serum hormone analysis

Reproductive steroid profiles in female (n=13) and male (n=5) red wolves (Canis rufus) were characterized in fecal samples collected during the breeding season (December—May) and over a 1 year period, respectively. Blood samples from females (n=12) also were collected during the periovulatory period for luteinizing hormone (LH) and steroid analysis. High performance liquid chromatography (HPLC) of fecal extracts determined that estradiol and estrone constituted the major and minor forms, respectively, of fecal estrogen metabolites. Although native progesterone was present, pregnane metabolites predominated as the major forms of fecal progestins. HPLC analysis of fecal extracts from males revealed no native testosterone, but rather the predominance of more polar androgen metabolites. Based on hormone profiles and/or pup production, females were classified as pregnant (n=3), ovulatory‐nonpregnant (n=9), or acyclic (n=3). Longitudinal monitoring of females indicated no pregnancy‐specific differences in concentrations of either fecal progestagen or estrogen metabolites compared to ovulatory‐nonpregnant individuals; however, baseline progestagen concentrations were consistently elevated in acyclic females. There was good correspondence between serum and fecal steroid concentration during the periovulatory period. A rise in serum estrogens preceded the ovulatory LH surge which was then followed by a significant progesterone rise during the luteal phase. In males, changes in fecal androgen metabolite concentrations coincided with photoperiod fluctuations, increasing in late autumn and reaching peak concentrations during mid‐ to late winter just before the start of the breeding season. Collectively, these results serve as a database of ovarian and testicular endocrine events in this species, which can be utilized in population management and application of assisted reproductive technologies. Zoo Biol 21:321–335, 2002. © 2002 Wiley‐Liss, Inc.     

Estradiol induces sexual behavior in female túngara frogs

Steroid hormones play an important role in regulating vertebrate sexual behavior. In frogs and toads, injections of exogenous gonadotropins, which stimulate steroid hormone production, are often used to induce reproductive behavior, but steroid hormones alone are not always sufficient. To determine which hormonal conditions promote sexual behavior in female túngara frogs, we assessed the effect of hormone manipulation on the probability of phonotaxis behavior toward conspecific calls in post-reproductive females. We injected females with human chorionic gonadotropin (HCG), estradiol, estradiol plus progesterone, saline, or HCG plus fadrozole (an aromatase blocker) and tested their responses to mating calls. We found that injections of HCG, estradiol, and estradiol plus progesterone all increased phonotaxis behavior, whereas injections of saline or HCG plus fadrozole did not. Since injections of estradiol alone were effective at increasing phonotaxis behavior, we concluded that estradiol is sufficient for the expression of phonotaxis behavior. Next, to determine if estradiol-injected females display the same behavioral preferences as naturally breeding females, we compared mating call preferences of naturally breeding females to those of post-reproductive females injected with estradiol. We found that, when injected with estradiol, females show similar call preferences as naturally breeding females, although they were less likely to respond across multiple phonotaxis tests. Overall, our results suggest that estradiol is sufficient for the expression of sexual responses to mating calls in túngara frogs. To our knowledge, ours is the only study to find that estradiol alone is capable of promoting phonotaxis behavior in a frog.     

Progestin receptors and the activation of female reproductive behavior: A critical review

Gonadal steroid hormones act upon the central nervous system (CNS) to regulate a variety of behavioral and neuroendocrine functions. Much attention has been focused on the mechanisms by which steroids interact with the brain to coordinate mammalian reproduction, particularly their role in the activation of mating behavior and in the feedback control of gonadotropin release. For example, female rodent reproductive behavior is abolished within a day or two following gonadectomy (Powers, 1970) and can be restored in a dose-dependent manner by exogenously administered estradiol and progesterone ( Boling and Blandau, 1939; Beach, 1942; Whalen, 1974). The molecular mechanisms underlying steroid induction of female rodent sexual behavior have been extensively investigated (for recent reviews see Feder, Landau, and Walker, 1979; McEwen, Davis, Parsons, and Pfaff, 1979; McEwen, 1981; Feder, 1984). To date, however, there is little conclusive evidence regarding the details of the molecular mechanisms by which estradiol and progesterone facilitate estrous behavior.     

Female polyandry affects their sons’ reproductive success in the red flour beetle Tribolium castaneum

A potential benefit to females mating with multiple males is the increased probability that their sons will inherit traits enhancing their pre‐ or post‐mating ability to obtain fertilizations. We allowed red flour beetle (Tribolium castaneum) females to mate on three consecutive days either repeatedly to the same male or to three different males. This procedure was carried out in 20 replicate lines, 10 established with wild‐type, and 10 with the Chicago black morph, a partially dominant phenotypic marker. The paternity achieved by the sons of females from polyandrous vs. monandrous lines of contrasting morph was assessed in the F1, F2 and F3 generation by mating wild‐type stock females to two experimental males and assigning the progeny to either sire based on phenotype. The sons of polyandrous wild‐type females achieved significantly higher paternity when mating in the second male role than the sons of monandrous wild‐type females. By contrast, when mating in the first male role, males produced by females from polyandrous lines tended to have lower paternity than males from monandrous lines. Both effects were independent of the number of mates of the black competitor’s mother, and interacted significantly with the number of progeny laid by the female. These results provide the first evidence that manipulating the number of mates of a female can influence her sons’ mating success and suggest a potential trade‐off between offence and defence in this species.     

Insights into ovarian function in wild muriqui monkeys (Brachyteles arachnoides)

Fecal samples were collected systematically during a 6-week period, from 13 September-24 October, 1990, from four nonlactating female muriquis (Brachyteles arachnoides) inhabiting an 800 ha forest at Fazenda Montes Claros in Minas Gerais, Brazil. All four females were experienced mothers; one had most recently given birth in June 1988; the other three had most recently given birth in August 1988. Fecal assays measuring progesterone, estradiol, and estrone indicated consistently low levels in the one female who had given birth in June 1988 and in two of the three females who had given birth in August 1988. Elevated steroid levels did, however, appear in fecal samples from the fourth female on day 15 of the collection period. Steroid levels subsequently dropped and then began to rise again during what appeared to be a second cycle. The cycling female was the only one of the four females examined observed to copulate during the collection period. These preliminary data indicate that nonlactating female muriquis do not cycle year-round, resumption of cycling is not tightly synchronized among females even when their prior parturitions were tightly synchronized, and resumed sexual activity appears to be associated with resumed cycling. © 1994 Wiley-Liss, Inc.     

Endocrine correlates of sexual behavior in the Mohor gazelle (Gazella dama mhorr)

In this study, we quantitatively examined male sexual behavior in relation to fecal estrogen and progesterone concentrations in female Mohor gazelles. We investigated the hypothesis that, during natural mating, males detect cues relating to the potential for successful conception and pregnancy. Time series analysis revealed that males could detect the approach of estrus 2-3 days before female fecal estrogens and estrogen/progestagen (E/P) ratio reached their peak values. Males also paid closer attention to those females excreting higher fecal estrogen concentrations. Mounting and copulation frequencies were positively correlated with both peri-ovulatory fecal estrogen concentrations, and the frequency of pre-copulatory courtship behaviors. These data suggested that males invest their reproductive effort selectively by mating the most fertile females, assuming that estrogen is a valid index of fertility. This assumption was investigated by examining sequential phases of the reproductive cycle for evidence that oocytes and follicles produced in a more estrogenic environment would lead to the formation of the most competent corpora lutea, thereby maximizing the chance of sustaining pregnancy. Associations between sexual behavior and hormone excretion support the hypothesis that males may use this mechanism to assess female fertility.     

社群压力对圈养雌性亚洲象动情的影响

亚洲象是中国一级濒危保护动物,改善圈养亚洲象的繁殖状况是亚洲象保护工作的重要内容之一。本研究旨在通过分析社群压力对圈养雌性亚洲象应激和动情状况的影响,从而探究圈养雌性亚洲象长期不动情的原因。通过放射性免疫法检测雌性亚洲象尿液中皮质醇、孕酮和雌二醇水平以及粪便中皮质醇和雌二醇水平,以雌激素水平反映亚洲象的动情状况,以皮质醇水平反映亚洲象的应激状态,以争斗行为和友好行为的发生情况反映圈养群体的社群压力。研究发现：(1)处于优势地位的个体表现出更多的斗争行为,处于从属地位的个体受到更多的攻击行为;(2)优势个体的皮质醇水平显著高于处于从属地位个体的皮质醇水平;(3)优势个体的雌二醇和孕酮具有小幅周期性波动,而从属个体的雌二醇和孕酮水平没有表现出明显的波动。从本研究结果可以看出圈养亚洲象群体中优势个体对从属个体的行为抑制可能是导致从属个体雌激素水平低,长期不能参与繁殖的原因。     

Role of aromatization in sexual differentiation: Effects of prenatal ATD treatment and neonatal castration

Pregnant female rats were administered either the aromatization inhibitor ATD (1,4,6-androstatriene-3,17-dione) or propylene glycol from Days 10 to 21 of gestation. On the day of birth one-half of the offspring from each group were gonadectomized. The remaining offspring were gonadectomized 35 days after birth. When adult the animals were given eight weekly mating tests following treatment with 2 or 8 μg of estradiol benzoate (EB) and 25 or 200 μg of progesterone (P). The probability of lordotic behavior as well as the frequency of ear-wiggle and hop and dart responses was measured. Prenatal ATD treatment resulted in a slight increase in lordotic behavior in the males. Lordotic potential was greatly facilitated by castration at birth. ATD treatment also increased the frequency of proceptive behaviors in males and combined ATD treatment and neonatal castration produced a dramatic increase in these behaviors. Prenatal ATD treatment and neonatal ovariectomy had only modest effects on the display of receptive and proceptive behaviors in females. Two weeks after the last test for female mating behaviors, the animals received daily injections of 200 μg of testosterone propionate. Four weekly tests for male-typical responses were given starting 1 week after the first injection. Prenatal ATD treatment did not markedly affect masculine behavior in the males. Castration at birth eliminated the ejaculatory response and reduced the frequency of mounting and intromission behavior. Prenatal ATD treatment and ovariectomy at birth had no appreciable effects on the display of male-typical behaviors in the females. Testosterone-stimulated masculine behavior of the female was similar to that of the male castrated at birth.     

Polyandrous behavior in Cerconota anonella Sepp (Lepidoptera: Oecophoridae)

Among insects polyandrous behavior is common and plays an important role in female reproductive output. The present study aimed to evaluate the mating frequency of the moth Cerconota anonella Sepp under laboratory conditions and to verify if polyandrous behavior is common in this species. Approximately 47% of females mated more than once. However they presented differences in the mating period (early or late). In general, precocious females were more frequent than late females (P < 0.001, Binomial test). Such results suggest that polyandry in C. anonella may be common in the field.     

Preference for an estrous female over a non-estrous female evinced by female rats requires dihydrotestosterone plus estradiol

The effects were studied of long-term treatment with testosterone metabolites (dihydrotestosterone, DHT, and estradiol, E2, in sc Silastic implants) on preference behavior of ovariectomized female rats for an estrous female over a non-estrous female. For measuring this behavior a residential plus-maze was used which harbored two ovariectomized “stimulus” females on the top of peripheral boxes, one of which was made estrus by injection of estradiol benzoate and progesterone. When both steroids (DHT plus E2) were circulating simultaneously they evoked preference for an estrous female, while neither steroid by itself sufficed. In earlier work with adult male rats castrated on the day of birth, E2 was effective in the absence of DHT. This sex difference, therefore, seems to have arisen before birth. Further, administration of DHT alone caused a profound lack of interest in both “stimulus” females, which cannot be fully explained by the reduced locomotor activity which has been found to be induced by DHT in earlier Studies.     

圈养山魈繁殖行为的观察

2001 年1～9 月, 在成都动物园用所有事件取样法对人工饲养状态下7 只(5 ♀♀, 2 ♂♂) 山魈的繁殖行为进行了观察。结果表明, 山魈的繁殖没有明显的季节性, 一年四季均发情繁殖, 月经周期为30.55 ±0.77 d (N = 11) , 行经期2.38 ±0.13 d (N = 16) ; 交配行为均发生在白天, 交配持续时间为14.90 ±0.34 s (N = 246) , 具有明显的交配模式, 其中碟牙、爬跨、插入和抽动4 种行为在每次交配中都出现, 交配姿势仅有背腹式一种; 孕期为171.13 ±4.19 d (N = 8) , 产前不废食; 分娩都在夜间进行, 产程2～3 h ; 育幼期哺乳时间随幼仔长大逐渐减少。