An experimental investigation of the pair bond in the callitrichid monkey,Saguinus labiatus

The strength and specificity of attraction between mated pairs of red-bellied tamarins (Saguinus labiatus) were tested in the laboratory. Test individuals were placed in a choice situation in which they could indicate their preference, by proximity and quality of behavior measures, to either their pair mate in an adjoining cage or an alternative in a second adjoining cage (same-sex animal, opposite-sex animal, or an empty cage). The test animals showed a significant preference to be in visual contact and proximity with their pair mates instead of the alternative when it was an animal of the same sex as the test individual or an empty cage. However, when the choice was between their pair mate and an animal of the opposite sex, no preference for their pair mate was apparent. No sex differences were found. It is concluded that attraction to a pair mate is not sufficient to maintain a pair bond, and when pairs ofS. labiatus breed monogamously, the pair relationship is likely to be maintained, at least in part, through aggression between same-sex individuals.     

The effects of familiarity and group size on mating preferences in the guppy,Poecilia reticulata

Abstract In recent years, it has become evident that frequency dependence in the attractiveness of a particular phenotype to mates can contribute to the maintenance of polymorphism. However, these preferences for rare and unfamiliar male phenotypes have only been demonstrated in small, controlled experiments. Here, we tested the preference for unfamiliar mates in groups of six to 96 individuals over 13 days, in the guppy (Poecilia reticulata). We observed individual behaviour in situ to test whether fish discriminate two unfamiliar individuals among many familiar ones. We found that unfamiliar males and females were preferred over the familiar fishes in all groups and that this effect decayed over time. Increasing group sizes and levels of sexual activity did not hamper the preference for unfamiliar mates, providing further support for the role of frequency dependent mate choice in the maintenance of trait polymorphism in natural populations.     

Effects of Pair-Bond and Social Context on Male–Female Interactions in Captive Titi Monkeys (Callicebus moloch, Primates: Cebidae)

In monogamous species, an abiding relationship between a specific adult male and a specific adult female is a defining feature of the social system. The interactions between these individuals are influenced by many factors, including not only the history of their relationship (for example, development of a mutual bond), but also the immediate effects of the prevailing social context (for example, presence and sex of extra‐pair conspecifics). In this study we examined the effects of an existing bond and of social context on interactions between adult heterosexual pairs of the monogamous titi monkeys (Callicebus moloch). Twelve adult males and 12 adult females were tested with their cagemates and with an unfamiliar partner of the opposite sex in five social contexts: (1) mated male–female pair; (2) unfamiliar pair; (3) single female; (4) single male; and (5) empty stimulus cage. Results show that mated pairs were more affiliative than unfamiliar pairs and differentiated social contexts more sharply. Males were more responsive to context than females. Distance between mates was less and physical contact was more frequent in the presence of male–female pairs or a single male, than in the presence of a single female or an empty cage. These findings suggest that the presence and sex of strangers have a stronger influence on male–female interactions when the pair has an existing relationship.     

Computer-assisted reconstruction of the mating pairs of Aspidisca (Protozoa,Ciliophora)

The ciliate Aspidisca shows a peculiar mating process during which the cytoplasmic bridge interconnecting the two mates, appears to vary in size and position. With the aid of a computer-assisted three-dimensional reconstruction of newly formed and advanced pairs, it was shown that at the beginning of the mating process, the walls of the bridge were formed only by the ventral surfaces of both mates. It was also shown that later on, the dorsal surface of one partner is involved. This finding is considered as surprising, considering that in the ciliates studied to date, the fusion between the two mates always occurs at the level of a well defined region of the ventral surface, which is therefore considered as being a highly specialized zone.     

Mated pairs of owl monkeys (Aotus nancymaae) exhibit sex differences in response to unfamiliar male and female conspecifics

In socially monogamous species, mate‐guarding could be a reproductive strategy that benefits both males and females, especially when males contribute to parental care. By actively guarding mates, males may reduce their chances of being cuckolded, whereas females that mate‐guard may reduce the likelihood that their mates will desert them or acquire additional mates, and hence limit or reduce paternal care of offspring. Owl monkeys (Aotus spp.) are socially monogamous with biparental care of young and, hence, potential beneficiaries of mate‐guarding. We presented mated pairs of captive owl monkeys (A. nancymaae) with unfamiliar male and female conspecifics, to determine if either member of the pair exhibits intraspecific aggression toward an intruder or stays close to its mate, behaviors indicative of mate‐guarding. Male mates were more responsible for the maintenance of close proximity between mates than females. Male mates also exhibited elevated levels of behavior that signify arousal when presented with a male conspecific. These responses by mated male owl monkeys are consistent with patterns that may help prevent cuckoldry. Am. J. Primatol. 72:942–950, 2010. © 2010 Wiley‐Liss, Inc.     

Karyotype of Saguinus labiatus labiatus (red-bellied marmosets)

The karyotype of Saguinus labiatus labiatus was determined by the Giemsa-banding technique on leukocytes cultured from 10 marmosets. The diploid chromosome number (2n = 46) was the same and the chromosome complement similar to other marmosets of genus Saguinus. Small karyotypic differences were found between S. l. labiatus and white-lipped marmosets (Saguinus fuscicollis) in the size of the X chromosome and in the banding pattern of one pair of metacentric chromosomes. A karyotypic variant was detected in 1 S. l. labiatus, characterized by a diploid chromosome number of 45 with balanced autosomal translocation involving two pairs of acrocentric chromosomes (T 16/19).     

Social organization,survival, and dispersal of cape foxes (Vulpes chama) in South Africa

We monitored 20 cape foxes (Vulpes chama) to determine the social organization, survival, and dispersal of this species on two sites in South Africa from 2005 to 2008. Cape foxes were socially monogamous and territorial, with annual home ranges of mated pairs (n = 8) overlapping 80% on average, compared to a mean overlap of 3% between foxes in adjacent ranges. At least 2 pairs remained associated for >1 breeding season, and both sexes exhibited strong site fidelity, as home ranges in consecutive years overlapped 58–98%. Members of mated pairs never foraged together, however they used the same or nearby (<100 m apart) day rests 81% of the time when pups were 0–4 months of age, but only 28% of the time during other months of the year. Dispersal was male biased, as all juvenile males (n = 6) dispersed when 9–11.5 months old, whereas 3 of 4 juvenile females remained philopatric as either breeders or non-breeding associates. At least 6 foxes bred as yearlings (3 F, 3 M), indicating cape foxes have high reproductive potential. Two adult females maintained their territories after their mates died, whereas two adult males dispersed soon after their mates died, indicating cape foxes likely have a female-based social organization. Annual survival was 0.64, and predation from larger carnivores, primarily black-backed jackals (Canis mesomelas), was responsible for 71% of mortalities. Our results provided empirical support for previous hypotheses regarding the relationship between body size and life-history patterns in Canidae, as several ecological parameters of cape foxes were similar to that of other small (<6 kg) canid species, especially Vulpes species inhabiting arid and semi-arid environments.     

Experimental study on sexual behavior between mother and son in Japanese monkeys (Macaca fuscata)

A mother, her adult son, four adult males and six adult females from a free-ranging group at Katsuyama were paired in a cage in the sexual seasons from 1976 to 1980. The paired subjects were classified into the following three types: mother and son, familiar pairs and unfamiliar pairs. The familiar pairs consisted of monkeys who had been in the Katsuyama group until about six months before the experiment. The unfamiliar pairs consisted of monkeys who had not met each other at all or who had not met each other for more than eight years before the experiment. Serial mounts which terminated with ejaculation occurred in nine of ten unfamiliar pairs, four of five familiar pairs, but there were none between the son and mother. The son and mother did not appear to be sexually aroused between themselves, although they were sexually active to other partners. However, on rare occasions, the son mounted singly on the mother, and on one occasion he ejaculated. Their interaction did not change essentially during the three years. The son rarely mounted serially on a female who had a close relationship with his mother.     

For whom the male calls: an effect of audience on contact call rate and repertoire in budgerigars, Melopsittacus undulatus

Budgerigars are well known for their ability to imitate sounds, but little is known about the functional contexts in which they use these imitations. Recently, we have shown that male budgerigars consistently imitate the contact calls of the females with whom they are paired. Here we investigate whether males produce these imitations more frequently when they are with their mates than when they are with other females. In one experiment, we established seven budgerigar pairs and then tested each male with his mate and with an unfamiliar female. In the second experiment, we allowed pairs to form freely in an aviary and then tested the males with their mate and with a familiar mated female. In both experiments, the males produced significantly more imitations of their mate's call (defined as calls that were more than 75% similar to the mate's predominant contact call) when they were with their mate than when they were recorded with another female. Under aviary conditions, this difference was due to both a general increase in the males' rate of calling and to an increase in the percentage of the males' calls that were imitations. These data show that male budgerigars modify their contact call rates and repertoires in an audience-specific manner. This audience effect is unusual because it involves a learned vocalization and is extremely specific to a particular audience, namely the mate. Copyright 2003 Published by Elsevier Science Ltd on behalf of The Association for the Study of Animal Behaviour.      

Attracting mates: Effects of paternal investment on mate attraction strategies

It is proposed here that mate-attraction strategies among females and among males vary facultatively with expectations about paternal investment. The following four hypotheses are argued and tested: 1. Females who expect to find investing mates will be more likely than other females to emphasize their need for investment by suppressing their resources and appearance of competence. 2. Females who expect to find investing mates will try to attract them by acting chaste and emphasizing their fidelity, while females who expect non-investing mates will flaunt their sexuality in order to get pre-reproductive investment from as many males as possible. 3. Males who think it is appropriate to invest heavily in offspring will be more likely than other males to attract mates by emphasizing their ability and willingness to invest. 4. Investing males will be more likely than non-investing males to emphasize chastity and fidelity, whereas non-investing males will flaunt their sexuality and sexual attractiveness to females.These hypotheses were evaluated among undergraduates by administering questionnaires measuring (a) attitudes toward paternal investment and (b) reported tactics used to attract mates. Hypotheses 2–4 were supported by the data, while hypothesis 1 received only partial support. The mixed results for hypothesis 1 indicate that self-deprecating acts and deferential acts may be signaling different things.     

An ethogram of the common marmoset (Calithrix jacchus jacchus): General behavioural repertoire

The behavioural repertoire of four captive breeding pairs of Callithrix jacchus jacchus is described. Social communication took the form of postures, facial expressions, vocalizations and piloerection displays. Detailed analyses were made of piloerection displays, adult play, copulatory, aggressive, and prey-catching behaviour. Aggressive behaviour was uncommon in adult mated pairs. Play between adults showed a degree of temporal organization. Vocalizations were the main methods of intragroup communication whilst piloerection displays were directed towards members of other groups and also to unfamiliar objects. The behavioural repertoire of C. jacchus jacchus is compared with that of other Primates.     

Pair-bond formation and breeding success in the common marmosetCallithrix jacchus jacchus

The breeding records from 22Callithrix jacchus jacchus females aged 13–23 months were examined. It was evident that females aged more than 18 months when first paired bred sooner, as did females paired with sexually experienced males. A detailed behavioral investigation of nine newly formed pairs was carried out for 10 weeks. Males showed more following, sniffing, tail-raised presents, and affectional behavior than their mates, while females showed more soliciting. Only females gave the submissive vocalization (ngÄ). This shows that there is a degree of sexual dimorphism in the behavior of this monogamous monkey. Four of the nine pairs failed to conceive within 12 weeks of pairing;the females of these pairs behaved more submissively than successful breeders, showing more ngÄ and less bristling and sexual behavior. In all cases the four females were housed in close proximity to dominant relatives and this was considered to be a significant factor.     

Kinship alters the effects of forced cohabitation on body weight,mate choice and fitness in the rat-like hamster Tscheskia triton

It has been documented that social isolation imparts deleterious effects on gregarious rodents species,but caging in group imparts such effects on solitary rodents. This study was attempted at examining how kinship to affect body weight,behavioral interaction,mate choice and fitness when we caged male and female rat-like hamsters Tscheskia triton in pair,a solitary species. We found that females paired with nonsibling males became heavier than the females paired with sibling males,but both agonistic and amicable behavior between paired males and females did not differ between sibling and nonsibling groups. This indicated that kinship might reduce females' obesity in response to forced cohabitation,and dissociation might exist between physiological and behavioral responses. Furthermore,binary choice tests revealed that social familiarity between either siblings or nonsiblings decreased their investigating time spent in opposite sex conspecific of cage mates and/or their scents as compared with those of nonmates,suggesting effects of social association on mate and kin selection of the hamsters. On the other side,both females and males caged in pair with siblings show a preference between unfamiliar siblings or their scents and the counterparts of nonsiblings after two month separation,indicating that the kin recognition of the hamsters might also rely on phenotype matching. In addition,cohabitation (or permanent presence of fathers) elicited a lower survival of pups in nonsibling pairs than sibling pairs,but did not affect litter size,suggesting that kinship affects fitness when housing male and female ratlike hamsters together. Therefore,inbreeding might be adapted for rare and endangered animals.     

Sexual dimorphism in responses to unfamiliar intruders in the tamarin, Saguinus oedipus

Aspects of social structure in group-living species can be inferred by observing the responses of individuals to unfamiliar animals. This study examined the responses of mated pairs of cotton-top tamarins (Saguinus oedipus oedipus) to presentation of either unfamiliar conspecifics or members of a related tamarin species, the saddle-back tamarin (Saguinus fuscicollis fuscicollis). Male and female responses to intruders differed: resident males threatened, displayed piloerection, approached, and attacked intruders, especially males, while resident females showed increases in suprapubic scentmarking in the presence of intruders. Both males and females discriminated between the species of intruders, exhibiting more threats, scent-marking, piloerection, and approaches in the presence of conspecific intruders. There are pronounced sex differences in the signals and behaviour patterns that are elicited in an aggressive or territorial encounter with unfamiliar conspecifics in this monogamous primate.     

Individual discrimination in the big-clawed snapping shrimp,Alpheus heterochelis

Rahman et al. (Rahman, N., Dunham, D.W. and Govind, C.K. (). Mate recognition and pairing in the big-clawed snapping shrimp, Alpheus herterochelis. Mar. Fresh. Behav. Physiol., 34, 213–226.) demonstrated discrimination by snapping shrimp between former mates and unfamiliar conspecifics, but did not test individual discrimination. In the present study, snapping shrimp showed discrimination between familiar and unfamiliar same-sex conspecifics by preferentially entering that arm of a Y-maze leading to familiar individuals. Furthermore, after being exposed to water from the home tanks of unknown individuals, they later showed an elevated response to this water, if the direction from which the water came into their tank was changed to be novel. This indicates that test subjects associated a familiar chemical stimulus with its location in the environment. This discrimination could only have been made if that chemical signature were recognised as different from that of another chemically familiar individual. This result also demonstrates that the water surrounding an individual contains sufficient (chemical) information to allow discrimination of one individual from another.     

Welfare of entire male pigs is improved by socialising piglets and keeping intact groups until slaughter

In today's production systems, pigs raised for slaughter are mixed many times, resulting in stress and fighting. The negative consequences of mixing are probably more severe with entire males than with castrates, as they fight more. In this project, we studied a system without castration where entire male pigs met unfamiliar pigs only once. Piglets from two litters were allowed to visit each other from circa 2 weeks of age through an opening between the farrowing pens. Entire males from these litters were kept in intact groups from weaning and onwards, and they were slaughtered pen-wise in intact groups. Control pigs were raised and weaned in their litters and mixed with unknown pigs when moved to the growing–finishing unit. They were slaughtered by split marketing based on individual weight. In total, 96 entire males from 24 litters were studied. Activity and social interactions of pigs were studied by direct observations on three observation occasions per pen for pigs kept in intact groups and four occasions for control pigs. All pigs were inspected for skin lesions during raising and at slaughter. Results showed that fewer pigs in intact groups were resting (17.1% v. 28.5%; P = 0.044) and they showed less aggressive behaviour (16.1 v. 27.7 number of interactions per hour; P = 0.001) than control pigs when moved to the growing–finishing unit. They also got fewer skin lesions compared with control pigs (15 v. 35; P < 0.001). Consequently, control pigs tended to grow slower during the 1st week after mixing; however, growth rate during the whole growing–finishing phase did not differ between treatments (P = 0.205). Control pigs directed more aggressive behaviour towards non-litter mates than towards litter mates during the whole growing–finishing phase, whereas pigs from the other treatment made no difference between litter mates and other familiar pigs. At 67 kg, there was more sexual behaviour (mounting) among control pigs (7.6 v. 3.4; P = 0.033), but after slaughter no differences were found in testis weight or boar taint compounds. At slaughter, more entire males that were slaughtered pen-wise and kept in intact groups were without skin lesions compared with the mixed control pigs (74% v. 13%; P < 0.001). This study shows that the welfare of entire male pigs can be improved by socialising piglets and by keeping them in intact groups during raising and at slaughter.     

Aggression and Affiliation during Social Conflict in Pigs

Social conflict is mostly studied in relation to aggression. A more integral approach, including aggressive and affiliative behaviour as well as physiology, may however give a better understanding of the animals'' experience during social conflict. The experience of social conflict may also be reflected in the spatial distribution between conspecifics. The objective was to assess the relationship between behaviour, physiology, and spatial integration in pigs (Sus scrofa) during social conflict. Hereto, 64 groups of pigs (9 wk of age) were studied in a 24 h regrouping test whereby pairs of familiar pigs were grouped with 2 unfamiliar pairs, in either barren or straw-enriched housing. Data on aggressive and affiliative behaviour, skin lesions, body weight, and haptoglobin could be summarized into three principal component analysis factors. These three factors were analysed in relation to spatial integration, i.e. inter-individual distances and lying in body contact. Pigs stayed up to 24 h after encounter in closer proximity to the familiar pig than to unfamiliar pigs. Pigs with a high factor 1 score were more inactive, gave little social nosing, had many skin lesions and a high body weight. They tended to space further away from the familiar pig (b = 1.9 cm; P = 0.08) and unfamiliar ones (b = 0.7 cm; P = 0.05). Pigs that were involved in much aggression (factor 2), and that had a strong increase in haptoglobin (factor 3), tended to be relatively most far away from unfamiliar pigs (b = 0.03 times further; P = 0.08). Results on lying in body contact were coherent with results on distances. Pigs in enriched housing spaced further apart than pigs in barren housing (P<0.001). The combined analysis of measures revealed animals that may either promote or slow down group cohesion, which may not have become clear from single parameters. This emphasizes the importance of an integral approach to social conflict.     

Extrapair fertilization and genetic similarity of social mates in the Mexican jay

Inbreeding depression should favor the ability of females toavoid inbreeding or minimize its effects. We tested for a relationshipbetween genetic similarity of social pairs and the occurrenceof extrapair fertilization (EPF) in the Mexican jay (Aphelocomaultramarina). Multilocus minisatellite and microsatellite DNAfingerprinting was used to detect extrapair young and measuregenetic similarity between social parents. We found that 12of 31 (39%) nests had at least one EPF and 15 of 93 (16%) youngwere the result of EPF. The mean DNA fingerprinting band sharingscore between social mates who had at least one EPF was significantlyhigher than the mean band sharing score between mates who didnot (0.35 versus 0.25). The mean band sharing score for non-EPFdyads (0.25) was similar to the background band sharing amongnonrelatives (0.23). The mean band sharing score for mates thathad an EPF was significantly higher than that of nonrelatives(background) and was significantly lower than that of half-siblings(0.52). Our results showed a highly significant relationshipbetween genetic similarity of social mates and incidence ofEPF.     

Factors affecting pair compatibility in captive kangaroo rats,Dipodomys heermanni

Captive propagation is a critical component of the Morro Bay Kangaroo Rat Recovery Plan, but past attempts to breed this and other kangaroo rat species have had mixed success. In three experiments using a closely related surrogate species, the Lompoc kangaroo rat, we evaluated the effects of familiarity and long-term housing experience on the behavior of captive males and females during dyadic encounters in an attempt to devise husbandry methods most conducive to reproduction. Females exhibited less aggression with and were more likely to allow physical contact with familiar males, provided the males had had previous social experience, such as that provided by living in close sensory contact with female conspecifics. Socialized males (those housed adjacent to females, separated from them by a wire mesh screen) were cautious, rather than persistent, when interacting with unfamiliar or anestrous females. Males housed in isolation from conspecifics were persistent whether or not they were familiar to the female. Pairs with very long periods of familiarity exhibited more nonaggressive contact than newly acquainted pairs. Results suggest that housing structures allowing longterm sensory contact between potential mates may improve breeding success in kangaroo rats and other solitary, aggressive species. © 1995 Wiley-Liss, Inc.

1 This article is a US Government work and, as such, is in the public domain in the United States of America.

     

Reproductive behavior and mate fidelity in the monogamous goby,Valenciennea longipinnis

Reproductive behavior and mate fidelity of the gobiid fish,Valenciennea longipinnis, were studied on the coral reef at Sesoko Island, Okinawa, Japan. These fish usually live in pairs, not only foraging together for benthic animals in sandy areas, but also constructing several burrows within their home range. Before spawning, both fish, although mainly the male, constructed a mound, piling up dead-coral fragments, pebbles, shells, sand and algae onto one of the burrows. After spawning an egg mass on the ceiling of the burrow, the female stayed outside and continued the construction and maintenance of the mound for 3–5 days until hatching, while the male tended the eggs inside. Mate guarding of females seemed to prevent males from monopolizing several females. Although some pairs showed mate fidelity through several spawnings, more than half of the pairs broke up after only one spawning. The pair bond was broken by mate desertion and the disappearance of each sex. Both sexes preferred larger spawning partners; larger females spawned more eggs and larger males provided better egg care. Mate desertion occurred when larger potential mates, relative to the current partner, became available. The frequency of solitary individuals was higher in males than in females, resulting in females deserting their mates more often than males. Two factors seem to have facilitated mate desertion: (1) occurrence of size mis-matched pairing and (2) overlapping home ranges.