The influence of females on male territorial dominance and female preference in dwelling place in laboratory mice

The influence of female mice (Mus musculus) on intermale aggression and the female choice between dominant and subordinate males were tested. Normal male mice were paired with a castrated male or a female. Two pairs of the same kind were housed together after acclimation for 3 days in half (home cage) of the apparatus, which was composed of eight cages connected by tunnels. One of the two normal males became dominant. The dominant males became more aggressive in the presence of females than in the presence of castrated males. The two normal males dwelt in their own home cages. The two females dwelt together and preferred to dwell in the home cages of the dominant male. The two castrated males dwelt together and seemed to decide their dwelling cage more freely than the subordinate normal male. Received: August 20, 1999 / Accepted: December 6, 1999     

Restoration of sexual performance in old rhesus macaques paired with a preferred female partner

Experiments were undertaken to determine whether the decline in the ejaculation frequency of old male rhesus macaques is due to a decrease in physical capacity. In the first experiment, the capacity of old males to ejaculate in a series of biweekly tests was investigated. Six old (18–23 years) and six young (8– 12 years) male rhesus macaques were given 10-min tests of sexual behavior with nine different females chosen at random. The old males were also given 10-min tests with a preferred female, 1339. When the old males were tested with nine different females, their sexual performance (e.g., frequency of ejaculation) was significantly less than that of the young males, but their performance was comparable to that of young males in nine tests with female 1339. In a second experiment, the capacity of old males to show repeated ejaculations over a 3-hr period was tested. The same old and young males were given a 3-hr test with female 1339. The sexual performances (number of ejaculatory series completed and behavior displayed within each ejaculatory series) of the old males did not differ significantly from those of the young. Also, no significant differences in behavior were observed between young and old males during the first 10 min of the 3-hr tests. Our data show that the decline in the sexual performance of old rhesus males is not due to a decreased capacity to perform sexually or to physical debilitation.     

Copulatory behaviour of the bank voleMyodes glareolus: matings with one and two males do not make a difference

In promiscuous species in which females mate with more than one male during oestrus, males may increase their sperm expenditure or change their copulatory behaviour in response to the risk of sperm competition. I used an experimental approach to investigate the pattern of copulatory behaviour of the bank voleMyodes glareolus Schreber, 1780 depending on whether the female mated with one or two males. The work showed that the copulatory period of the bank vole lasted about 80 minutes and consisted of 4–5 ejaculatory series, with multiple intromissions preceding ejaculation. There were no significant changes in number of intromissions across the first four ejaculatory series, but I did find a relationship between number of intromissions and first ejaculation latency; also, ejaculation latencies grew shorter as the ejaculatory series proceeded. Litter size did not differ significantly between females that mated with one male and those mating with two, nor did the reproductive success of males that mated with the same female. Mating with an oestrus female appears to be advantageous for bank vole males even if they mate as the second one, and the risk of sperm competition did not trigger changes in male copulatory behaviour. The similar durations of the copulatory period and patterns of change of ejaculation latencies during copulations with one and two males point to the role of the female in temporal copulatory behaviour of the bank vole.     

Suppressed copulatory behavior and ovarian function in lactating Japanese monkeys (Macaca fuscata fuscata) during the mating season

The influence of lactation on copulatory behaviors and ovarian functions was studied in Japanese monkeys (Macaca fuscata fuscata) during the mating season. Three lactating females were housed in an outdoor group cage with their infants, and three nonlactating females were housed in an adjacent outdoor cage. They were mated by introduction of one of four rotationally chosen males into the females' cage, for two hours three times a week; the occurrence of ejaculatory copulations was recorded. Blood samples were collected on each observation day, and plasma levels of estradiol, progesterone, and luteinizing hormone (LH) were measured by specific radioimmunoassays. In nonlactating females, plasma estradiol increased during the transition into the mating season, and rose to levels over 90 pg/ml for the first time on about 50 days before the first ovulation. Shortly after plasma estradiol exceeded 90 pg/ml in the nonlactating females, the onset of ejaculatory copulations occurred. They received ejaculations continuously up to the early ovarian luteal phase. On the other hand, in lactating females, there were lower levels of plasma estradiol (below 90 pg/ml) during the transition into the mating season, and they received no ejaculation during that period. Two of the three lactating females ovulated only once, and they received ejaculations only during the periovulatory period, coinciding with the rise of their plasma estradiol levels over 90 pg/ml. The remaining lactating female remained anovulatory and received no ejaculation throughout the entire mating season. These results have demonstrated that the low sexual activity of lactating females is clearly correlated with low levels of plasma estradiol due to suppressed ovarian function.     

Influence of androgen in the neonatal period on ejaculatory and postejaculatory behavior in the rat

The objective of the present report was to investigate the influence of androgen in the neonatal period on the development of ejaculatory and postejaculatory behavior. At birth, male rats were either castrated (neonatally castrated males), implanted with a Silastic tube of the aromatase inhibitor androsta-1,4,6-triene-3,17-dione for the first 10 days (ATD males), or left untreated (normal males). Female rats were either injected with 0.5 mg testosterone propionate (TP) on Days 1 (day of birth) and 2 (androgenized females) or left untreated (normal females). All gonadally intact animals were castrated at 60 days of age. Following TP administration, all animals were tested for ejaculatory and postejaculatory behavior under both shock and nonshock conditions. All animals were capable of showing the intromission pattern; however, the ejaculatory pattern was exhibited regularly only by those animals exposed to androgen at birth (normal males, androgenized females, and ATD males). The normal males required fewer intromissions to achieve ejaculation than the other two groups exhibiting this reflex. This result is discussed in terms of peripheral genital stimulation deficits and the differentiation of neural tissue responsible for masculine copulatory behavior. Androgenized females and ATD males displayed a refractory period, characterized by 22-kHz vocalizations, equal to or longer than that found in normal males. These results indicate that defeminization is not necessary for the display of normal ejaculatory and postejaculatory behavior.     

High-resolution X-ray computed tomography scanning of primate copulatory plugs

In this study, high-resolution computed tomography X-ray scanning was used to scan ring-tailed lemur (Lemur catta) copulatory plugs. This method produced accurate measures of plug volume and surface area, but was not useful for visualizing plug internal structure. Copulatory plug size was of interest because it may relate to male fertilization success. Copulatory plugs form from coagulated ejaculate, and are routinely displaced in this species by the penis of a subsequent mate during copulation (Parga [2003] Int. J. Primatol. 24:889-899). Because one potential function of these plugs may be to preclude or delay other males' successful insemination of females, we tested the hypothesis that larger plugs are more difficult for subsequent males to displace. Plugs were collected opportunistically upon displacement during data collection on L. catta mating behavior on St. Catherines Island, Georgia (USA) during two subsequent breeding seasons. Copulatory plugs exhibited a wide range of volumes: 1,758-5,013.6 mm3 (n = 9). Intraindividual differences in plug volume were sometimes greater than interindividual differences. Contrary to predictions, larger plugs were not more time-consuming for males to displace via penile intromission during copulation. Nor were plugs with longer vaginal residence times notably smaller than plugs with shorter residence times, as might be expected if plugs disintegrate while releasing sperm (Asdell [1946] Patterns of Mammalian Reproduction; Ithaca: Comstock). We found a significant inverse correlation between number of copulatory mounts leading to ejaculation and copulatory plug volume. This may indicate that if males are sufficiently sexually aroused to reach ejaculation in fewer mounts, they tend to produce ejaculates of greater volume.     

Scrounging facilitates social learning in common marmosets, Callithrix jacchus

The minimalistic environment of standard laboratory cages can adversely influence the responses of animals in standard behavioural tests and other aspects of the animals' biology. To avoid this, cages should provide for the animals' species-specific behavioural characteristics. We hypothesized that, given their possible capacity for colour vision, laboratory mice, Mus musculus, would show preferences between cages of different colours. Studies show that environmental colour can influence emotionality and task performance in humans, suggesting that cage colour could also affect emotionality and performance of mice in behavioural tests. Seventy-two mice were housed in home cages painted red, black, green or white. Five weeks later, 24 mice were placed individually into an apparatus allowing them to choose between cages of each of the home cage colours. Each mouse showed a highly significant preference, which overall, was unrelated to home cage colour. White cages were most preferred and red were least. Home cage colour had a significant effect on body weight and food consumption as well as on behaviour in a raised plus maze. Mice from red home cages spent most time in the closed arms, indicating greater anxiety, possibly suggesting that the reduced occupancy of the red preference cages resulted from avoidance of environmental conditions that induced a negative mental state. These findings show that laboratory mice have strong preferences between cages of different colours. We also found that an apparently inconsequential environmental variable, home cage colour, can influence responses in standard behavioural tests, which should be considered in assessing the external validity of such tests. Copyright 2003 The Association for the Study of Animal Behaviour. Published by Elsevier Ltd. All rights reserved.     

Postcastration retention of sexual behaviour in the male BDF1 mouse: The role of experience

Male BDF₁ mice (the F₁ progeny of a cross between C57BL/6 females with DBA/2 males) show a remarkable retention of sexual behaviour following castration. Two experiments were conducted to describe in detail the postcastration copulatory performance of the BDF₁ male mouse and to determine to what extent such performance is influenced by experience prior to castration. Experiment I found that castration leads to significant increases in the number of mounts and intromissions needed to reach ejaculation, and to a significant increase in ejaculation latency. Experiment II found that although precastrational sexual experience is not essential for the performance of the ejaculatory reflex after castration, it does influence the frequency of its occurrence. Furthermore, type of postweaning social experience influenced the display of ejaculatory behaviour by non-experienced castrates, as those with female social experience were superior to those with social experience with males or no social experience. The interactions of experience, hormones and genotype in the control of sexual behaviour in the BDF₁ male are discussed.     

Sexual behaviour and reproductive competition in male wild and domestic Norway rats

The copulatory behaviour of male wild Norway rats (Rattus norvegicus) exposed individually to females in hormone-induced oestrus is characterized by fewer mounts and intromissions per ejaculatory series, shorter ejaculation latencies, and longer ejaculatory clasps than the copulatory behaviour of domestic males. Competition between wild and domestic males tested simultaneously in pairs produced only minor changes in copulatory behaviour. The reproductive success of wild and domestic male pairs simultaneously exposed to naturally cycling females was nearly equal in both the laboratory and an outdoor enclosure. Genotype of the female had little effect on male copulatory behaviour. The copulatory behaviour of sexually naive and experienced domestic rats did not differ. However, most sexually naive wild males failed to exhibit copulatory behaviour under the test conditions employed.     

Transient hypertension and sustained tachycardia in mice housed individually in metabolism cages

The novel environment of a metabolic cage can be stressful for rodents, but few studies have attempted to quantify this stress-response. Therefore, we determined the effects on mean arterial pressure (MAP) and heart rate (HR), of placing mice of both sexes in metabolism cages for 2 days. After surgical implantation of a carotid artery catheter mice recovered individually in standard cages for 5 days. Mice then spent 2 days in metabolism cages. MAP and HR were monitored in the standard cage on Day 5 and in metabolism cages on Days 6-7. MAP increased by 18+/-3 and 22+/-4 %, while HR increased by 27+/-4 and 27+/-6 %, in males and females, respectively, during the first hours after cage switch. MAP decreased to baseline in the fourth and eighth h following metabolism cage switch in males and females, respectively. However, HR remained significantly elevated in both sexes during the entire two-day period in metabolism cages. Females had lower MAP than males both pre- and post-metabolism cage switch, but there were no sex differences in HR. These results demonstrate sustained changes in cardiovascular function when mice are housed in metabolism cages, which could potentially affect renal function.     

云南拉沙山黑白仰鼻猴交配行为和出生季节

灵长类的交配模式对于了解和掌握雄性的交配策略和社群的稳定机制非常重要,但是目前有关亚洲灵长类交配模式的数据较少;因此,该研究于2011年1—12月,分别采用全事件取样法和焦点动物瞬时扫描取样法收集了拉沙山黑白仰鼻猴群的交配行为和出生数据。猴群全年交配,有2个峰期,一个是繁殖交配高峰期(8一10月);另一个在出生季节,但其非繁殖交配的生物学意义尚不清楚。雌性通过俯卧/注视雄性或跳落邀配。爬跨射精比为8.8,射精交配稀少(11.4%),这说明雄性并非每次交配都射精,因而支持黑白仰鼻猴交配模式的主体为多次爬跨射精或处于从单次爬跨射精到多次爬跨射精连续谱上段的观点。雄性邀配的射精爬跨多于雌性,说明多次爬跨射精不仅是雄性的一个交配策略,而且可以决定交配模式在连续谱的位置。交配时间后延6~7个月,交配频次与婴猴出生率相关。拉沙山猴群出生模式为严格的季节性,这进一步证实了前人的观点。婴猴出生具有一定的同步性,且不同猴群婴猴出生的同步模式不同。     

Physiological profile of juvenile rats: effects of cage size and cage density

Although there is a general consensus that housing conditions affect the well-being of laboratory animals, the ideal cage size and density for housing laboratory rodents has not been established. The authors investigated the effects of cage size and cage density on growth, organ development, metabolic profile, and hemogram in juvenile Sprague-Dawley rats. Larger cages and increased cage density were associated with depressions in body weight and in the weights of several organs. In general, increasing group size and density correlated more strongly with detrimental effects on the growth of females than males, although hemogram values indicated that males are more prone to emotional stress and immune suppression than females in response to increasing group size and crowding.     

Male siblings inhibit reproductive activity in female pine voles, Microtus pinetorum

Pine vole females paired in breeding cages with male siblings remain unreproductive beyond the age of puberty onset. In this study only 10% of females caged with their brothers reproduced, whereas 85% of females placed with strange males had litters. Mating between a female and a strange male was also suppressed by the presence of a male sibling sequestered behind a wire mesh barrier in the breeding cage. When the sibling male was removed from the cage after 1 day, 78% of the females produced litters. When the sibling remained behind the barrier in the breeding cage, only 42% gave birth to young conceived in his presence. Conception of second litters during the postpartum estrus occurred in over 80% of females caged with strange males alone and only 10% of females caged with sibling males. Female pine voles are induced to become reproductively active by strange males but this activity is depressed by the presence of a brother, and once initiated it does not continue if the female is caged with her brother.     

Existence of an ejaculatory-like reaction in ewes ovariectomized and treated with androgens in adulthood

The complete behavioral repertoire of male sexual activity can be observed during daily androgen treatment (testosterone propionate, 15 mg/day) of normal ewes ovariectomized as adults. This includes the ejaculatory pattern (deep thrust accompanied by a rapid backwards movement of the head) which is followed by a dramatic decrease in the frequency of sexual interactions, similar to the male's postejaculatory reduction of activity. However, the sexual performances of the genetic females remain lower than those of normal males in ejaculation latency, postejaculation latency, and mount/ejaculation ratio.     

Influence of androgen on the development of sexual behavior in rats : I. Time of administration and masculine copulatory responses, penile reflexes, and androgen receptors in females

The objective of the present study was to investigate the effect of the time of administration of androgen, during the neonatal period, on the development of masculine copulatory behavior in female rats. In addition, the influence of androgen, administered neonatally, on the development of penile reflexes and cytoplasmic androgen receptor levels in the hypothalamic-preoptic area (HPOA) was examined. Female rats were injected with 0.5 mg testosterone propionate (TP) at either 1, 8, or 24 hr after birth and again 24 hr after the first injection. Fifty percent of the females treated with TP at 1 and 8 hr after birth displayed the ejaculatory response when tested in adulthood. In contrast, 93 and 87.5% of oil-treated males and females, respectively, which were androgenized at 24 hr after birth exhibited this response. The results indicate that a considerable amount of masculinization occurs postnatally in the rat. However, none of the androgenized females displayed any penile reflexes even when tested following the display of an ejaculatory response. HPOA androgen receptor levels were somewhat higher in the oil-treated females than in males but were not correlated with the ability to exhibit ejaculation patterns.     

Presence of platelet-activating factor in rhesus (Macaca mulatta) spermatozoa.

Platelet-activating factor [1-O-alkyl-2-acetyl-sn-glycero-phosphocholine; PAF] is a unique signaling phospholipid which has been implicated in a number of biological activities (e.g., reproduction). PAF has been detected in the spermatozoa from a number of laboratory and domestic species, including, but not limited to, rabbit, bovine, and the mouse. The concentration of PAF is inversely related to human (Homo sapien) spermatozoal quality. Additionally, PAF levels are significantly higher in Bolivian squirrel monkey (Saimiri sciureus) spermatozoa obtained during the breeding season than spermatozoa obtained during the nonbreeding season. There are no reports on the presence of PAF in rhesus (Macaca mulatta) spermatozoa. Therefore, the primary objective of this study was to detect the presence of PAF in rhesus spermatozoa. A second objective was to determine if PAF spermatozoa levels differ between animals housed individually (single-caged) versus free-ranging (open corrals). Semen were collected from mature rhesus via electro-ejaculation. Spermatozoa were washed free of ejaculatory plug and quick frozen in PBS. Endogenous lipids were extracted from thawed spermatozoa and ejaculatory plugs then assayed for the presence of PAF by [125I]-radioimmunoassay. PAF was not detected in any ejaculatory plugs. PAF levels were significantly higher (P < 0.01) in spermatozoa obtained from free-ranging males (mean: 1.16 pmol/10(6) spermatozoa) than males housed individually in single cage units (mean: 0.53 pmol/10(6) spermatozoa). PAF was present in rhesus spermatozoa. Additionally, PAF levels were higher in spermatozoa obtained from corral-housed animals. Additional studies are warranted to elucidate the role of PAF in spermatozoa function.     

Calibration and evaluation of field cage for oviposition study with Aedes (Stegomyia) aegypti female (L.) (Diptera: Culicidae)

Differences among results gathered from insect behavior studies conducted in laboratory and field situations are due to ambient variables that differ greatly between both environments. In laboratory studies the environmental conditions can be controlled whereas in field temperature, humidity and air velocity vary uncontrollably. The objective of this study was to calibrate and evaluate an experimental area (field cage) (14 x 7 x 3.5 m) subdivided into eight test cages (2.5 x 2.5 x 2 m) for use in behavioral oviposition tests of Aedes aegypti (L.) mosquitoes for developing a new methodology to assess attractants and oviposition traps. Test cage calibration involved: (1) minimal experiment duration tests; (2) optimal female release number per traps test and (3) trap placement tests. All tests used gravid A. aegypti females; 3-4 days post blood meal and the sticky trap MosquiTRAP to catch adults. Ninety percent of the females released were recaptured 2h after the beginning of the experiment, and this allowed up to 32 test repetitions/day to be conducted in the field cage. The minimum number of females necessary to conduct statistical analyses was 20 females/trap/test per cage. No significant difference was found in the behavioral response of gravid females to four different trap positions within test cages. Field trapping results with attractant were similar to those in the field cage. Therefore, the field cage could replace field trapping for evaluating at least mosquito traps and oviposition attractants for A. aegypti.     

Dominance status of adult male Japanese macaques: Relationship to female dominance status,male mating behaviour,seasonal changes,and developmental changes

Aggressive dominance orders of all adults in a confined troop of Japanese macaques (Macaca fuscata) were determined each mating and birth season during a 4-year interval. Males outranked more females in the mating than in the birth season, and some males shifted back and forth from ranks lower than female ranks in the birth season to ranks higher than female ranks in the mating season. Mating behaviour (number of female partners in mount and ejaculation series and ejaculation frequency) did not differ among males with ranks higher than, as high as, or lower than those of most females, nor did individual males mate more in years, when they were high-ranking than in years when they were not. There was a correlation, however, between ejaculation frequency and the number of females defeated by males. A pattern of increasing male rank with age was found.     

Home ranges of European mink<Emphasis Type="Italic">Mustela lutreola</Emphasis> in southwestern Europe

We radiotracked 7 European minkMustela lutreola Linnaeus, 1761 (5 males and 2 females), to determine their distribution, size and temporal changes of their home range in an area of southwestern Europe, where American minkM. vison was not established. Size of home ranges varied from 11 to 17 km along watercourses in males and were 0.6 and 3.6 km in females. Home ranges of males were larger than those found in previous studies. Most females captured (either radiotracked or not) were found within the home range of males. Males occupied adjoining river sections with minimal range overlap, suggesting an intrasexually exclusive spacing pattern for males. Each month males used new river stretches, mainly along tributaries; meanwhile they showed a steady use of their stem river section. Resting sites were mainly beneath dense brambles ofRubus patches located in the river bank.     

Hormonal and social factors affecting evoked sexual behavior in Rhesus monkeys

Male rhesus monkey sexual behavior occurring spontaneously or evoked by remotely-controlled hypothalamic stimulation was studied in dominant and subdominant males with both dominant and subdominant, estrogen-treated or untreated, ovariectomized females. The behavior was quantified in terms of number and duration of ejaculatory sequences, number of thrusts, and number of mounts per sequence. Little or no spontaneous sexual behavior was observed with an untreated ovariectomized female. However, evoked sexual behavior with the exception of evoked ejaculation could be obtained whether the females were treated or untreated. Spontaneous and evoked sexual behavior was directed towards both dominant and subdominant females. The female chosen by the male was in part determined by the dominance status of the female. Evoked sexual behavior differed from spontaneous behavior in terms of an increased number of thrusts per mount, an increased number of ejaculations per session, and a decrease in latency between ejaculatory sequences.