What makes male mice paternal?

Both copulation and postcopulatory cohabitation with pregnant females reduce infanticide and enhance paternal responsiveness in male CS1 mice. The effectiveness of copulation in this process, however, depends on the number of occasions that males have previously encountered infants. Infanticidal males which have been subordinated in brief encounters with other males are less likely to commit infanticide in subsequent tests than are those which became dominant to other males. Males which copulate and cohabit with a relatively large female are less likely to be infanticidal than are those with a relatively small female. These data suggest that males are subordinated after copulation by their mates and that this subordination is a factor in the reduction of infanticide and the initiation of paternal responsiveness.     

Maternal aggression toward infanticidal males of different social status in wild house mice (Mus musculus domesticus)

Maternal aggression was examined in wild female mice (Mus musculus domesticus) derived from animals trapped in Alberta, Canada. Lactating females were tested for their behavior toward intruder males during the time of postpartum estrus while housed in a two-cage apparatus containing a defensible nest area. Prior to being used as intruders, sexually naive males were screened for their behavior toward a newborn pup (83% exhibited infanticide). Only infanticidal males were then housed in pairs and allowed to establish a dominance hierarchy. Dominance status was further verified by a urine marking test. The dominant and subordinate infanticidal males were then placed into a lactating female's cage and observed for 1 hr. The test was terminated immediately when a male began to attack the pups. Lactating females attacked the males in both groups, but subordinate males received more intense attacks than dominant males. Dominant males elicited significantly more fear/defense behavior than subordinate intruders. All of the dominant males and only one submissive male attacked the pups. Females were thus successful in blocking infanticide only by infanticidal subordinate males. Since females do not persist in attacking males with high fighting ability, one function of maternal aggression could be to assess the fighting, and resource holding, potential of a future mate. © 1994 Wiley-Liss, Inc.     

Male-related chemical cues promote sexual receptivity in the female musk shrew

The role of conspecific chemical cues in the activation of sexual behavior was investigated in the female musk shrew (Suncus murinus). In Experiment 1, virgin female musk shrews were exposed to either clean cages or cages recently vacated by an adult male. Regardless of whether the male used for the sexual behavior test was "familiar" to the female (having spent the 24 h exposure in his vacant cage) or "unfamiliar," females exposed to male-related cues received mounts from males significantly sooner than females exposed to clean cages. In Experiment 2, females housed for 24 h in a cage soiled by an adult male allowed males to mount significantly sooner than females housed in a cage soiled by a castrated male, another female, or a clean cage. These results demonstrate that chemical cues, produced exclusively by adult males, promote sexual receptivity in female musk shrews.     

The relationship between infanticide and pregnancy block in mice

Newly pregnant mice are more likely to exhibit pregnancy block when females are exposed to infanticidal males rather than to noninfanticidal males. These data suggest that females are able to assess the risk to their future infants and adjust their reproductive tactic. Those females that did not exhibit pregnancy block in the presence of infanticidal males suffered a greater loss of pups than those in the presence of noninfanticidal males, demonstrating the advantage of pregnancy block. Females served by infanticidal or noninfanticidal males showed no difference in pregnancy block, but if the litter was produced, there was a greater loss of pups sired by infanticidal males.     

Sex differences in aggressive behaviour in various strains of mice

Two nonalbino inbred (C57 BL/6 and C3H/He) and one albino strain (Swiss) of mice were compared for female aggression toward intruders: 1 in period of lactation, 2 in nonlactating state and (3) in nonlactating state but previously rubbed with urine of lactating females; and for male aggression toward familiar or unfamiliar opponents. The results showed that resident females of the C57 and Swiss strain vigorously attack lactating intruders introduced into their cages. This effect was mediated by urinary cues emitted by the latter mice. It was also shown that Swiss residents displayed aggression towards nonlactating females, irrespective of their strain. Groups of C57 residents reacted most aggressively towards Swiss females, less aggressively towards C3H intruders, but did not show any aggression towards their own nonlactating conspecifics. In contrast, none of the C3H resident female groups displayed aggression towards intruding females of any category or strain. The results also showed that the males of the three strains displayed little (Swiss and C3H) or no aggression (C57) towards familiar opponents, whereas they directed increased aggressive responses towards unfamiliar ones. Comparisons among the three strains of mice revealed that Swiss males were the most aggressive in either situation. On the other hand, the finding that C3H males showed aggressive responses suggested that male and female aggression are, in this strain, under separate genetic or hormonal control.     

Olfactory self-recognition in a cichlid fish

Animal self-cognizance might be of importance in different contexts like territoriality, self-referent mate-choice or kin recognition. We investigated whether the cichlid fish Pelvicachromis taeniatus is able to recognize own olfactory cues. P. taeniatus is a cave breeding fish with pronounced brood care and social behavior. In the experiments we gave male cave owners the choice between two caves in which we introduced scented water. In a first experiment males preferred caves with their own odor over caves with the odor of an unfamiliar, unrelated male. To examine whether self-recognition is based rather on individual or on family cues we conducted two further experiments in which males could choose between their own odor and the odor of a familiar brother and between the odor of a familiar brother and an unfamiliar, unrelated male, respectively. Males preferred their own odor over that of a familiar brother suggesting individual self-referencing. Interestingly, males (at least outbred ones) preferred the odor of an unfamiliar, unrelated male over that of a familiar brother, maybe to avoid competition with kin. We discuss the results in the context of animal self-cognizance. All experiments were conducted with in- and outbred fish. Inbreeding did not negatively affect self-recognition.     

Nestling recognition via direct cues by parental male bluegill sunfish (<Emphasis Type="Italic">Lepomis macrochirus</Emphasis>)

Parental care can be costly to a parent in terms of both time and energy invested in the young. In species with cuckoldry or brood parasitism not all of the young under a parent's care are necessarily offspring. In such cases, distinguishing between kin and non-kin, and investing only in the former (nepotism), can be advantageous. Bluegill sunfish (Lepomis macrochirus) are characterized by paternal care and cuckoldry, and care-providing males appear to show nepotistic behaviours. Here, we investigated nestling recognition in bluegill, determining whether parental males can differentiate between young from their own nest (familiar and related) and young from non-neighbouring nests (unfamiliar and unrelated) using (1) visual and chemical cues, and (2) chemical cues only. In the first experiment, wild-caught parental males were presented with samples of eggs or fry (newly hatched eggs) collected from their own nest or a foreign nest and placed on opposite sides of an aquarium. The time these parental males spent associating with each sample, and their "pecking" behaviours (indicating cannibalism), were recorded. Parental males showed no preference between eggs from their own nest and eggs from a non-neighbouring nest, but they preferred to associate with fry from their own nest over foreign fry. There also was a positive relationship between male body size and the time spent associated with fry from their own nest. Parental males pecked at foreign fry more than 5 times as often as fry from their own nest, though this difference was not statistically significant. In the second experiment, fry that were collected from the nest of a wild-caught parental male or a non-neighbouring nest were placed in different containers and the water from each was dripped into opposite ends of an aquarium. The time the male spent on each side was recorded. In this case, parental males spent more time near the source of water conditioned by unrelated fry, but there was a positive relationship between male condition (fat reserves) and the time he spent near the source of water conditioned by fry from his own nest. Results confirm that chemicals cue nestling recognition by parental male bluegill. Electronic Publication     

The potential effects of protected nests and cage complexity on maternal aggression in house mice

I studied the behavior of nursing house mice (Mus musculus) in captivity and used a two-by-two factorial design to test the hypothesis that the combination of a protected nest along with a chance for the intruders to retreat would improve the ability of resident females to defend their litters from infanticidal males. A chance for the intruder to retreat was manipulated by testing the resident females in either a single- or a two-compartment cage. The effect of a protected nest was examined by providing females with a nest box having a narrow entrance. During each test, an infanticidal adult male was introduced into the cage of a resident female and her pups. I observed that neither the presence of a protected nest nor the chance for the intruders to retreat to a different compartment, or a combination of the two, increased the ability of a female to defend her litter against an intruder male. Moreover, neither of these two factors influenced the overall behavior of the resident females. I obtained similar results after using data from previous studies to examine the influence of both of these factors on the efficiency of maternal aggression. Overall, these two approaches showed that females are often unable to prevent intruders from committing infanticide. I discuss the validity of the hypothesis that maternal aggression evolved as a mechanism to protect offspring from infanticide. Aggr. Behav. 24:385–396, 1998. © 1998 Wiley-Liss, Inc.     

Paternal behavior in the spiny mouse (Acomys cahirinus)

The responsiveness of adult male spiny mice (Acomys cahirinus) to both their own and alien precocial young was investigated. Paternal behavior was manifested primarily by the males huddling with their offspring and the coordination of pup attendance between adult males and females. With less than 2 days exposure to their own neonates, males were found to discriminate between their own and alien young. Experience plays an important role in the development of paternal behavior in spiny mice. Males who have never had pups of their own sniff and attack unfamiliar neonates more than males who have fathered pups. The adaptive significance of paternal investment in this uniquely precocial murid rodent was discussed.     

Does fear modulate defensive and offensive types of maternal attack in mice?

Swiss CD‐1 lactating mice show a different pattern of attack toward intruders of differing sex, displaying defensive attack against the male (bites on the head and ventrum associated with fear) and offensive attack against the female (bites on the back and flanks with no elicitation of fear). This dichotomy may reflect diverse functions of maternal aggression: the attack toward males (the more infanticidal gender in laboratory strains) has been interpreted as a counterstrategy to infanticide, whereas the attack toward females may serve to establish a social hierarchy or to space rivals of the same sex. In terms of proximal mechanisms, fear may be a key factor involved in the modulation of the different patterns of attack. In Experiment 1 we compared the pattern of attack of lactating females in Swiss CD‐1 and Wild mice toward male and female intruders in relation to fear components of behavior of the attacking dams. Results showed that in Swiss mice, male intruders were attacked with a defensive type of attack accompanied by high levels of fear, whereas female intruders did not elicit fear in the attacking animal but were attacked with an offensive pattern. In Wild mice, both types of intruders were attacked with a defensive pattern; notwithstanding, fear was evident only toward male intruders. This suggests that fear is not totally responsible for the expression of the defensive type of attack. To test the hypothesis that defensive attack toward male and female intruders may be related to the infanticidal potential of the intruder, Experiment 2 examined levels of infanticide in both male and female Swiss CD‐1 and Wild mice. Swiss female mice showed virtually no infanticidal behavior, whereas Swiss males and both sexes of Wild mice showed similarly high levels of infanticide (55%–75%). From a game theory perspective, the defensive pattern of maternal attack toward female intruders in Wild mice is discussed as “extreme” defense of a high value resource and thus, functionally, a competitive form of aggression. Aggr. Behav. 26:193–203, 2000. © 2000 Wiley‐Liss, Inc.     

The Effect of Social-Comparison Feedback on Aggressive Responses to Erotic and Aggressive Films1

A study assessed the effects of social-comparison cues and filmed violence on aggression toward women. Under the auspices of validating some film clips for use in future research, males viewed either erotic, violent sexual, or violent nonsexual films. A male confederate provided social comparison feedback by indicating (or not indicating) that the film degraded women. Self-reports of sexual arousal, affective responses to the films, perceptions of violence, perceptions of pornography, and perceptions of portrayal of women were measured. In a purportedly unrelated learning experiment, males were given the opportunity to aggress toward a female confederate through electric shock. Intensity and duration of shock were measured. Social comparison information caused reductions in self-reports of sexual arousal, affect, and increased perceptions of violence in the erotic film condition only. Social-comparison information caused males to rate the depiction of women as more negative in both the erotic and violent nonsexual conditions. Regardless of film type, social comparison information caused a reduction in perceived realism of the films. Only film condition affected perceptions of pornography, with greater sexual content judged as more pornographic. Social-comparison information reduced the intensity of shocks delivered. Finally, social-comparison information led to reduced duration of shock in all film conditions; however, this effect appeared to dissipate in the violent sexual condition. Implications are discussed.     

Short-term early exposure to pups alters infanticide in adulthood in male but not in female wild house mice (Mus domesticus)

Male and female wild house mice (Mus domesticus) were allowed to remain in the cage of their parents until 30-35 days of age. When a second litter was delivered, the first litter was exposed to the younger pups for 2-10 days. In adulthood the male and female mice that had been exposed to pups as juveniles and an additional group that had cohabitated with their parents for the same length of time but were not exposed to pups were tested for infanticidal behavior. The frequency of infanticide by the adult female mice was not significantly different (55% vs. 70%, respectively). In contrast, the adult males that were exposed to pups as juveniles were significantly less likely to kill young in adulthood when compared with males that were not similarly exposed (35% vs. 80%, respectively). These data further demonstrate the strong influence of experience on the expression of infanticide by male mice and its relative unimportance to the expression of female infanticide.     

Ultrasonic vocalizing by adult female mice (Mus musculus)

Though an extensive body of literature exists concerning the emission of 70-kHz ultrasonic vocalizations by adult male mice (Mus musculus), almost nothing is known about the ultrasonic vocalizing of adult females. A series of five experiments was conducted to examine adult female mouse ultrasound emission. Results indicated female ultrasonic vocalizing to be typically displayed among female mouse dyads and comparable to the ultrasonic vocalizing levels obtained among male-female pairs. Genotypically based variations in the production of ultrasounds by females were also noted. Like male mice, socially naive females readily ultrasonically vocalized to anesthetized female conspecifics and rarely vocalized to anesthetized males. Unlike males, socially experienced females emitted few ultrasounds to either female urine or female-soiled cage shavings. Although social experience served to increase the ultrasound emission of male mice to female sex cues, the production of ultrasounds by females to these cues was decreased by social experience. Implications with regard to the existence of a behavioral/functional sexual dimorphism in adult mouse ultrasonic vocalizing are discussed.     

Gender-specific social experiences and the development of aggressive and sexual behavior in male mice

This study examined influences of gender-specific social experiences on the development of aggressive and sexual behavior in male mice. To determine the effects of gender-specific social experience three different types of groups were constituted after the animals had been weaned. The subjects were randomly assigned to different treatments. Female groups were composed of one experimental male and three female cohabitants. Male groups were composed of five experimental males each, and the mixed-sex groups were composed of two experimental males and of two females. The experimental subjects stayed in these groups until the age of approximately three months, when the testing for sexual and aggressive behavior commenced. For the sexuality tests, a receptive female was placed in the home cage of the experimental male for ten minutes. A nonaggressive male was placed in the home cage of the experimental male for seven minutes for the aggression tests. The experimental males were administered both sexuality and aggression tests, the sequence of testing sexual and aggressive behavior was systematically varied in order to control the influence of the two different types of behavioral tests. The results showed that males with only male social experiences showed fewer responses and were less active in both the aggression and sexuality tests than the males from the two other types of groups. Significant positive correlations between activity during aggression and sexual tests were obtained for all three groups. © 1994 Wiley-Liss, Inc.     

Infanticide by genetically deaf mice: Possible evidence for an inhibiting function of pups' ultrasonic calls

The influence of pup ultrasonic calls on male infanticidal behavior was evaluated by using mice of the GFF strain which includes two different lines: a normally hearing line and a genetically deaf line. Deaf male mice exhibited more infanticidal behavior than mice with normal hearing. In addition, deaf pups, which emitted fewer ultrasonic calls than normal pups, suffered a higher, even though not significant, rate of infanticidal behavior by normally hearing males. On the whole, these results question Labov's hypothesis that pups emit few ultrasounds in the presence of strange males in order to avoid being located and killed by them.     

Effects of female odors on the sexual behavior of male hamsters

A series of experiments was undertaken to investigate the effects of removal of several scent glands and scent-producing organs of female hamsters on the copulatory performance of male hamsters. In the first experiment it was shown that males engage in less copulatory activity toward females lacking vaginal secretions than toward females with these odors. Eliminating visual cues by observing pairs under infrared illumination did not change the performance of males toward these two kinds of females. The results of Experiment 2 indicated the importance of flank, ear, and Harderian glands as well as vaginal secretions--males showed the highest levels of copulatory behavior toward females with a full complement of odors and the lowest levels toward those lacking three of four sources of scent. Similar results were obtained in the third experiment in which anesthetized females were used as stimulus animals to increase the importance of chemical cues and to reduce variability due to the behavior of females. The sexual behavior of males was greatest toward females with all sources of scent present, lower toward those lacking vaginal secretions, and still lower toward those lacking vaginal secretions and other sources of odors. In the fourth experiment we asked whether any one of the nonvaginal scent glands was particularly important in stimulating male sexual behavior, but we found no differences in male performance toward females that lacked vaginal secretions or that in addition lacked one of the other scent glands. In the fifth experiment males displayed higher levels of sexual behavior toward vaginectomized females than toward vaginectomized females that had been deodorized by a cleaning procedure, again indicating the importance of nonvaginal odors in stimulating copulatory performance. Thus these experiments demonstrate the importance of vaginal secretions in the sexual arousal of male hamsters, a role for nonvaginal odors in sexual arousal of males, and the lack of necessity of these odors for male copulatory behavior. These results have implications for theories of olfactory communication in mammals and for interpretations of experiments in which lesions of the olfactory system lead to deficits in male copulatory performance.     

父子(女)间面孔相似性的进化适应机制及其影响

由于受精和孕育过程发生在母亲体内, 人类受孕具有一定的隐蔽性, 同时人类早期社会存在着通奸行为, 因而, 父亲面临着父亲身份不确定性的风险。为了应对这种风险, 人类男性在生活中往往会寻求一些能表征父亲身份的线索, 其中亲子间面孔相似性被证明是辨别个体间是否存在基因关联(或血缘关系)的有效线索之一。morph软件合成、第三方评定以及当事人的主观评定是研究亲子间面孔相似性的三种基本范式。以往的研究表明当父子(女)间面孔相似性越高时, 父亲对子女的亲子投资水平越高, 父亲感知到的焦虑水平越低, 父亲的身体也越健康, 与此同时, 当父子(女)间面孔相似性越高时, 父亲对女儿会表现出更高的性厌恶水平。未来的研究可以进一步关注文化因素在该效应中的调节作用, 探寻新的研究范式以提高研究的内部效度和外部效度, 以及探讨影响亲子间面孔相似性感知的因素。     

Social and environmental factors influence the suppression of pup-directed aggression and development of paternal behavior in captive meadow voles (Microtus pennsylvanicus)

During summer, female meadow voles (Microtus pennsylvanicus) maintain territories and males do not engage in paternal care. As day length shortens, territories dissolve and males nest with females and young. Because paternal behavior has never been studied in free-living meadow voles during colder months or in the laboratory under short photoperiods, the authors examined whether males housed in short day (SD) lengths exhibited more frequent or better quality paternal behavior than males housed in long day (LD) lengths. Sexually and parentally inexperienced (naive) SD males exhibited proportionally more and qualitatively better paternal care than naive LD males. SD males were more responsive than LD males to classic social cues associated with prepartum aggression inhibition and paternal onset. SD sires also displayed qualitatively better paternal behavior than LD sires. These data suggest that meadow vole paternal state is regulated by specific social and environmental cues that may contain reliable information about ecological conditions that favor paternal care.     

The decline of aggressiveness in male mice during group caging as determined by punishment delivered by the cage mates

Group-housed rodents are generally less aggressive than isolated counterparts. The present study examined the role of defeat by cage mates as a reason for this decline in aggressiveness. In Experiment I, highly aggressive isolated male mice were introduced into aggressive or nonaggressive resident groups. The intruder's level of aggressiveness directed toward a group-housed standard opponent declined more rapidly after daily exposure to the aggressive than to the nonaggressive groups. Intruders in the aggressive groups received more attacks from their cage mates, and delivered fewer attacks to them than did the intruders in the nonaggressive groups. In Experiment II, the intruders lived for seven days in small wire net cages in the middle of the group cages. Their level of aggressiveness toward standard opponents decreased little during the preexposure but after being put freely into the groups, their aggressiveness declined to a minimal level within a day. Experiment III showed that when the wire net protection in the middle of the cage was installed after the group caging experience, the aggressiveness of the intruders did not return to the isolation level as effectively as it did in isolation. This is explained by the aggression-inhibiting content that the cues from the cage mates have acquired during group caging. The decline of aggressiveness in male mice during group caging is determined by punishment delivered by the cage mates.     

The sexual responses of sexual sadists

On average, rapists show greater relative genital responses to rape stories than do nonrapists in the laboratory. It has been suggested that this robust group difference is explained by the fact that many rapists are sexually sadistic. It is not clear, however, what the critical cues underlying rapists' genital responses are, because rape stories used in previous research include a mix of sadistic cues of violence and victim injury as well as cues of victim resistance and nonconsent. The present study was conducted to identify the critical cues producing self-identified sadists' sexual responses, and thereby to test sexual sadism as an explanation of rapists' arousal pattern. The present study was also conducted to develop a new phallometric test for sexual sadism for research and clinical applications, given evidence of poor diagnostic reliability and validity. Eighteen self-identified male sadists, 22 men with some sadistic interests who did not meet all of our sadist criteria, and 23 nonsadists (all recruited from the community) were compared in their genital and subjective responses to a new set of stories that disentangle violence/injury cues from resistance/nonconsent cues. The three groups differed in both their genital and subjective responses: using indices of relative responding, sadists responded significantly more to cues of violence/injury than nonsadists and men with some sadistic interests. The group difference for cues of nonconsent was not significant. The results suggest that sexual sadism primarily involves arousal to violence/injury in a sexual context rather than resistance/nonconsent. (PsycINFO Database Record (c) 2012 APA, all rights reserved).