Infanticide in male laboratory mice: Effects of social status,prior sexual experience,and basis for discrimination between related and unrelated young

Several aspects of infanticide, including effects of social status, prior sexual experience, and the basis for discrimination between related and unrelated young, were examined in Swiss-Webster laboratory mice (Mus musculus). Strange males introduced into the female's cage for 24 h on day 1 postpartum significantly reduced pup survival whereas the introduction of sires did not. Direct observations of infanticide were frequent, and the motor patterns used by males to kill pups are described. Males killed their own offspring when those young were in the nest of a strange female, whereas most males did not kill unrelated young in the nest of a familiar female. Thus, past association with the mother appears to be the single most important factor mediating male discrimination of young. Prior contact with a specific female's urine reduced a male's propensity for subsequently killing her young. The act of copulation itself also reduced infanticide. Infanticidal behaviour was correlated with the male's social status: most dominant males killed unrelated pups, whereas none of the subordinates engaged in infanticide. These results are discussed in terms of the population biology of this species.     

The libidinous newt. An analysis of variations in the sexual behaviour of the male smooth newt, Triturus vulgaris

In an experiment designed to investigate variations in the behaviour of male newts in response to female behaviour, five males were tested for each of forty consecutive days in a standard 5-min trial in which the female's behaviour was controlled by the experimenter. In all males there was a steady decline over the 40 days in the number of spermatophores produced, i.e. the number of sexual sequences completed during the 5-min trial period. A number of scores relating to the frequency of performance of male acts and to their temporal patterning are shown to be correlated with one another and with spermatophore score. The temporal patterning of the male's behaviour in a given sequence is related both to the total number of sequences completed in a trial and to the position of the sequence in question within the trial. Principal components analysis enables a number of correlated scores for a sequence to be expressed as the ‘libido’ score for that sequence. A number of factors which may influence the temporal patterning of the male's behaviour are discussed, and it is suggested that the amount of sperm available and the need to ascend to the surface to breathe may be the most important.     

Women's genital sexual arousal to oral versus penetrative heterosexual sex varies with menstrual cycle phase at first exposure

Reproductive-aged women show increased interest in sexual activity during the fertile phase of the menstrual cycle that can motivate sexual behavior and thereby increase the likelihood of conception. We examined whether women demonstrated greater sexual responses (subjective and genital sexual arousal) to penetrative versus oral sexual activities during the fertile versus non-fertile phases of their cycles, and whether women's arousal responses were influenced by the phase during which they were first exposed to these sexual stimuli (e.g., Slob et al., 1991; Wallen and Rupp, 2010). Twenty-two androphilic women completed two identical sexual arousal assessments in which genital responses were measured with a vaginal photoplethysmograph and their feelings of sexual arousal were recorded. Women viewed an array of 90 s films varying by couple type (female–female, male–male, female–male) and sexual activity type (oral or penetrative), during the fertile (follicular) and non-fertile (luteal) phases of their menstrual cycle, with the order of cycle phase at the first testing session counter-balanced. Women tested first in the fertile phase showed significantly greater genital arousal to female–male penetrative versus oral sex in both testing sessions, whereas self-reports of sexual arousal were not affected by cycle phase or testing order. These results contribute to a growing body of research suggesting that fertility status at first exposure to sexual stimuli has a significant effect on subsequent sexual responses to sexual stimuli, and that this effect may differ for subjective versus genital sexual arousal.     

Behaviors associated with tube-sharing in Microdeutopus gryllotalpa (Costa) (Crustacea:Amphipoda)

An earlier study showed that the onset of precopulatory behavior, or tube-sharing, in the amphipod crustacean Microdeutopus gryllotalpa (Costa) generally occurred toward the end of the females' intermolt period. Tube-sharing ended when the female molted and copulation occurred. It was hypothesized that after copulation the male would leave the female's tube, travel to another receptive female's tube, and begin tube-sharing with the new female (the “cruising male hypothesis”).The present study confirms this hypothesis for laboratory cultures. In addition, the study describes a female-typical and male-specific behavior (“blocking” and “intermittent pleopod beats”). These behaviors are only expressed during interactions between one individual who is entering, and another individual who is residing in the tube.     

The pattern of tube-sharing in Micro deutopus gryllotalpa (Crustacea: Amphipoda)

The amphipod crustacean Microdeutopus gryllotalpa builds tubes on solid substrata. Mature animals usually reside in individual tubes. When more than one individual is present in a tube it is always a single heterogametic pair. Tube-sharing occurs with the greatest frequency 12 h before the female's moult. Following the female's moult, most males leave the tube. The pattern of tube-sharing is the behavioural analoque of precopulation in epibenthic amphipods. It is demonstrated that (1) no more than two individuals are found in a tube because (2) one individual will not permit another individual of the same sex to cohabit the same tube, and (3) the female determines the time of tube-sharing, for most females tube-share only shortly before they moult. It is hypothesized that after the male leaves the female's tube, he cruises from tube to tube until he gains entry into the tube of another receptive female.     

Bayesian mating decisions in an amphipod, Gammarus lawrencianus Bousfield

In G. lawrencianus, females of a given fecundity and proximity to copulation day are assessed by males to be more valuable as mates, the longer the males have amplexed with the females (i.e. the greater their past investment in the act of amplexus). This behaviour is consistent with the hypotheses that (1) males are uncertain of the true reproductive state of a female on first contacting her; (2) the prior distribution of unamplexed females likely to be encountered by the males affects their initial estimates of a female's state; and (3) the time spent amplexing with a female allows information to be gathered which reduces a male's uncertainty of the female's state.     

Cooperation and conflict among dunnocks, Prunella modularis, in a variable mating system

The mating system of a population of 90 breeding dunnocks (or hedge sparrow, Prunella modularis) included monogamy, polygyny, polyandry and polygynandry. Monogamous males guarded females during their fertile period to prevent neighbouring males from copulating. The most intense guarding occurred where two (unrelated) males shared a territory. Here, the alpha male tried to prevent the beta male from copulating with the female. Beta males were seen to copulate in only half the cases. They were more likely to succeed when the alpha male found it difficult to guard the female closely because her range was large, the vegetation was dense or there were other females breeding synchronously on the same territory. Close guarding and chasing by males reduced the female's feeding rate and was correlated with unhatched eggs in the nest. Females attempted to escape the alpha male's attentions and actively encouraged the beta male to mate. Beta males only helped to feed the young if they copulated with the female. Nestlings fed by two males and a female got more food and weighed more than those fed by just one male and a female. Indirect evidence suggested that when beta males failed to copulate, they destroyed eggs or young chicks. Females laid larger clutches when two males mated with them as opposed to one, thus adapting their clutch size to the amount of parental care they expected. The results of natural removal experiments and matched comparisons of the same female in different mating systems support these conclusions. For females, selection favours cooperative polyandry, whereas for males if favours polygyny; the variable mating system may reflect the different outcomes of this sexual conflict.     

Intrasexual Competition and Mating Behavior in <Emphasis Type="Italic">Ptomascopus morio</Emphasis> (Coleoptera: Silphidae Nicrophorinae)

In nicrophorine beetles, genus Nicrophorus care their larva using small vertebrate carrion, whereas genus Ptomaucopusreproduce with small vertebrate carrion but show no parental care. Aggression and sexual behavior were examined in Ptomascopus morio and Nicrophorus quadripunctatus. Nicrophorus quadripunctatus had intense female–female as well as male–male contests. In Ptomascopus morio, by contrast, female–female aggression was rarely observed. Male–male aggression (pushing, biting, male–male mounting) in Ptomascopus morio was observed when a resource for breeding was present, whether or not a female was present. The lack of female–female aggression, and male–male aggression when resources but not females are present, suggest that the mating system of Ptomascopus morio is resource defense polygyny. Large males of Ptomascopus morio were also found to exhibit mate choice, preferring large females over small females.     

Système endocrine et physiologie de la diapause imaginale chez le criquet égyptien, Anacridium aegyptium

The Egyptian locust, Anacridium aegyptium, has four protocerebral neurosecretory centres: the A to B neurosecretory cells of the pars intercerebralis (the A cells are rich in fuchsinophil material and the B cells are devoid of fuchsinophil neurosecretion), the voluminous C neurosecretory cells poor in neurosecretion, and the median sub-ocellar neurosecretory cells.From September to the beginning of January, imaginal diapause is characterized by an accumulation of the median neurosecretion in the pars intercerebralis-corpora cardiaca system, by small corpora allata, and, in the female, by a stop in oöcyte development although the male's sexual activity is still not altered. Allatectomy suppresses neither the male's sexual behaviour nor its fecundity. From January, the increase of the photoperiod causes a release of the median neurosecretion in both sexes, an increase of the volume of the corpora allata, and breaks ovarian diapause.In autumn, the implantation of the male's or female's corpora allata of Anacridium does not stimulate ovarian growth of diapausing females. On the contrary, the implantation of corpora allata or of pars intercerebralis or of corpora cardiaca of Locusta migratoria migratorioides (locust without diapause) causes ovarian development of the diapausing females of Anacridium. Thus, in the two sexes of the Egyptian locust, the corpora allata are inactive during the female ovarian diapause. The imaginal diapause of Anacridium affects both sexes (stocking of median neurosecretion, arrest of the corpora allata). If diapause does not seem to affect the male's development, it is because its sexual activity is free from the pars intercerebralis and corpora allata.The corpora allata of Anacridium show a sexual dimorphism in the active adult: they are smaller in the male and have more mitosis in the female. An explanation of this dimorphism is advanced.     

Pre-copulatory behaviour in the male Mongolian gerbil: I. Differences in dependence on androgen of component patterns

Male behaviour patterns, including ultrasonics, olfactory investigation, grooming and sequences of following of oestrous females during the pre-copulatory period, were described for the Mongolian gerbil. Differences in dependence of these patterns on gonadal hormones were examined by measuring the rates of decline after castration and the degree of restoration following the subcutaneous injection of testosterone propionate (20 μg/2 days/animal). Castration and androgen therapy did not influence the performance of male genital grooming, allogrooming and the olfactory investigation of both female secretory products and the female's body, excluding the posterio-dorsal area. The other male patterns differed in the extent to which they were affected. Thus ventral gland marking, foot-stomping and sequences of follow/dart interactions declined rapidly and were not restored to pre-castration levels by androgen; whereas the upsweep ultrasonic vocalization and olfactory investigation of the female's perineal area declined more gradually, and were completely restored. These consistent differences in both decline and restoration suggest that mechanisms underlying some pre-copulatory patterns are influenced by androgen to a greater degree than others.     

Fertile women evaluate male bodies as more attractive,regardless of masculinity

Ovulatory cycle shifts in women's mate preferences have been documented for several physical and behavioral traits. Research suggests that, at peak fertility, women tend to prefer men with characteristics that reflect good genes for short-term sexual relationships. However, existing findings have been criticized for methodological flexibility and failing attempts to replicate core results. In a large (N = 157), pre-registered, within-subject study spanning two ovulatory cycles, we investigated cycle shifts in women's mate preferences for masculine bodies. Using a large set of natural stimuli, we found that when fertile, women's ratings of male bodies increased for sexual as well as for long-term attractiveness. Both effects were partially mediated by the estradiol-to-progesterone-ratio. Furthermore, moderation analyses revealed that both shifts were only evident in women in relationships, but not in singles. Contrary to previous findings, male masculine traits did not interact with cycle phase to predict attraction, indicating that women's preferential priorities do not shift. Taken together, our results do not support women's mate preference shifts, as assumed by the good genes ovulatory shift hypothesis, but are consistent with shifting motivational priorities throughout the cycle. Implications of these results for female estrus theories and methodological recommendations for future research are discussed.     

Reproductive skew drives patterns of sexual dimorphism in sponge-dwelling snapping shrimps

Sexual dimorphism is typically a result of strong sexual selection on male traits used in male–male competition and subsequent female choice. However, in social species where reproduction is monopolized by one or a few individuals in a group, selection on secondary sexual characteristics may be strong in both sexes. Indeed, sexual dimorphism is reduced in many cooperatively breeding vertebrates and eusocial insects with totipotent workers, presumably because of increased selection on female traits. Here, we examined the relationship between sexual dimorphism and sociality in eight species of Synalpheus snapping shrimps that vary in social structure and degree of reproductive skew. In species where reproduction was shared more equitably, most members of both sexes were physiologically capable of breeding. However, in species where reproduction was monopolized by a single individual, a large proportion of females—but not males—were reproductively inactive, suggesting stronger reproductive suppression and conflict among females. Moreover, as skew increased across species, proportional size of the major chela—the primary antagonistic weapon in snapping shrimps—increased among females and sexual dimorphism in major chela size declined. Thus, as reproductive skew increases among Synalpheus, female–female competition over reproduction appears to increase, resulting in decreased sexual dimorphism in weapon size.     

Female and male genetic contributions to post-mating immune defence in female Drosophila melanogaster

Post-mating reduction in immune defence is common in female insects, and a trade-off between mating and immunity could affect the evolution of immunity. In this work, we tested the capacity of virgin and mated female Drosophila melanogaster to defend against infection by four bacterial pathogens. We found that female D. melanogaster suffer post-mating immunosuppression in a pathogen-dependent manner. The effect of mating was seen after infection with two bacterial pathogens (Providencia rettgeri and Providencia alcalifaciens), though not after infection with two other bacteria (Enterococcus faecalis and Pseudomonas aeruginosa). We then asked whether the evolution of post-mating immunosuppression is primarily a ‘female’ or ‘male’ trait by assaying for genetic variation among females for the degree of post-mating immune suppression they experience and among males for the level of post-mating immunosuppression they elicit in their mates. We also assayed for an interaction between male and female genotypes to test the specific hypothesis that the evolution of a trade-off between mating and immune defence in females might be being driven by sexual conflict. We found that females, but not males, harbour significant genetic variation for post-mating immunosuppression, and we did not detect an interaction between female and male genotypes. We thus conclude that post-mating immune depression is predominantly a ‘female’ trait, and find no evidence that it is evolving under sexual conflict.     

Who suppresses female sexuality? An examination of support for Islamic veiling in a secular Muslim democracy as a function of sex and offspring sex

Whether it is men or women who suppress female sexuality has important implications for understanding gendered relations, ultimately providing insight into one widespread cause of female disadvantage. The question of which sex suppresses female sexuality more avidly, however, neglects that our interests are never unambiguously masculine or feminine; each of us has a combination of male and female kin which alters how much of our future fitness derive from each sex. Here we exploit a nationally representative sample of 600 Tunisians to test whether support for Islamic veiling—a proxy for female sexual suppression—is more common amongst one sex than the other, and is affected by the relative sex of one's offspring (i.e., the number of sons relative to daughters). We find that men are more supportive of Islamic veiling than women, but women with more sons are more supportive of veiling and more likely to wear veils than women with fewer sons. All effects were robust to the inclusion of religiosity, which was weaker amongst men and unrelated to the number of sons a woman had. The number of daughters affected neither religiosity nor support for veiling, but did increase women's likelihood of wearing contemporary, fashionable Tunisian veils compared with no head covering. We further found that men were more religious if they had more sons. Overall, these findings highlight that far from being the fixed strategy of one sex or the other, female sexual suppression manifests facultatively to promote one's reproductive interests directly or indirectly by creating conditions beneficial to one's descendent kin. These results show that both men and women can suppress female sexuality, although the function in either case appears more closely aligned with male rather than female interests.     

Female and male interactions during courtship in Calopteryx maculata and C. dimidiata (Odonata: Calopterygidae): Influence of oviposition behaviour

Calopteryx maculata and C. dimidiata damselfly females respond to male courtship with specific displays which signal differences in their receptivity. These include a rejection (wing spreading) and an invitation (wing-flipping) display, as well as a neutral (sit still) response. There are interspecific differences in the likelihood of each female display and in male responses to these displays. C. maculata males persist in courtship irrespective of female response, while C. dimidiata males generally stop courting when the female's response is rejection or neutrality. I suggest that these differences result from interspecific differences in oviposition behaviour. Female C. maculata oviposit at the water surface, which exposes them to disturbance by males attempting to mate. Females are therefore likely to remate to secure postcopulatory guarding when changing oviposition sites and males are expected to be persistent in courtship. Female C. dimidiata submerge to oviposit, which frees them from male disturbance and means that males have less control over female access to oviposition sites. Males therefore have less influence on mating by females and are expected not to persist in courtship of non-receptive females.     

Role of interflash intervals in a firefly courtship (Photinus macdermotti)

The flash code of Photinus macdermotti fireflies has been measured over a temperature range of 16 to 25°C. The code changes in characteristics fashion during different phases of firefly courtship. Males produce rhythmic patrolling flashes while flying, and when answered, shift to courtship flash pairs of significantly shorter interval. Females will answer some consecutive patrolling flashes and normally respond after the second flash of each male courtship pair. A possible behavioural role for the shifting of male patrolling and courtship flash intervals and for the female's response patterns is proposed.     

The pairbond in klipspringer

Like many small African antelopes, klipspringer (Oreotragus oreotragus) live in territorial pairs. The structure of the pairbond and the ways in which it is maintained through time are described quantitatively, using data on co-ordination of behaviour, activity budgets, progression orders and visual monitoring. Although both partners play an active role, the female's behaviour tends to be more concerned with efficient foraging, while the male's behaviour seems to emphasize those activities that allow him to maintain, contact with the female. Because the male needs to spend less time feeding than does the female, he detects predators more frequently, a behaviour that probably allows the female to feed more efficiently. Both sexes apparently defend the territory against intruders, although the functional significance of the territory remains unclear.     

Sexual behaviour and its olfactory control in the desert woodrat (Neotoma lepida lepida)

In studies 1 and 2 nine pairs of desert woodrats (Neotoma lepida lepida) were observed for copulatory behaviour when the female was in a state of naturally occurring oestrus (study 1) and following ovariectomy and oestrogen and progesterone replacement (study 2). Males and females respond in a similar way under conditions of natural and hormone-induced oestrus. Males show a consummatory pattern involving multiple mounts and ejaculations, with ejaculations occurring after single intromissions. Females show the lordosis reflex accompanied by hop-and-dart and ear-wiggling responses. In addition, both sexes show appetitive precopulatory behaviours; the male emits an audible rasping vocalization as he trails and mounts the female, following a period of intense sniffing of the female's anogenital region. The female also frequently approaches and sniffs the male. In study 3, the role of female odours in the sexual behaviour of the male was examined in eight of the nine pairs used in studies 1 and 2. This was done by applying to the anogenital region of ovariectomized females a combination of urine and vaginal secretions taken from familiar and unfamiliar, and oestrogen-primed or non-oestrogen-primed females. The results show that odours from oestrogen-primed females are not sufficient to elicit male sexual behaviour, if the female is not sexually active. In study 4 the eight males were tested for their preferences for urine and vaginal secretion odours taken from females in different reproductive states and applied to cotton swabs. These males spent more time sniffing unfamiliar oestrous odours than unfamiliar non-oestrous odours and more time sniffing oestrous odours from a familiar female over those taken from an unfamiliar female.In study 5, 12 sexually active males were tested with oestrogen-primed females before and after either olfactory bulb removal or sham-surgery. Bulbectomized animals ceased copulating with females although females showed precopulatory approaches.Taken together, these studies suggest that normal sexual behaviour in the male woodrat requires that the female both possess the attractive odours (of oestrus) and that she engage in appetitive precopulatory behaviour.     

The effects of mate separation on pair re-formation in the Texas cichlid fish (Cichlasoma cyanoguttatum)

This study tested whether mated pairs of Texas cichlid ($\text{Cichlasoma cyanoquttatum}$) would reform and continue rearing their offspring after being separated for either one, four, or ten days. All pairs successfully re-formed after one day, while only 50% re-formed after 4 days. No pair re-formed after 10 days of separation. In successfully re-formed pairs, the female was always more aggressive than her mate, irrespective of whether the female was the resident or the returning individual. Aggressiveness seemed related to the female's attempt to control the male's parental behavior. For pairs which did not re-form, the resident parent, either the male or female, violently and continously attacked the returned mate.     

Mating relationships and breeding suppression in the dwarf mongoose

Dwarf mongooses live in packs containing a dominant breeding pair. The alpha female produces litters at regular intervals, usually three times per year. Other sexually mature females come into oestrus in synchrony with the alpha female and occasionally become pregnant but may not raise their offspring. Some females which had not been visibly pregnant nursed the young of other females. Early in the alpha female's oestrous cycle the alpha male maintains proximity and copulates with her exclusively, attacking any other adult males which approach. Later he also copulates with other adult females and the beta male mates with the alpha female. The alpha pair are likely to be the parents of the great majority of young born in the pack.