Adult Female Pairs Research Articles

Activity and social factors affect cohesion among individuals in female Japanese macaques: A simultaneous focal‐follow study

Understanding cohesion among individuals within a group is necessary to reveal the social system of group-living primates. Japanese macaques (Macaca fuscata) are female-philopatric primates that reside in social groups. We investigated whether individual activity and social factors can affect spatio-temporal cohesion in wild female Japanese macaques. We conducted behavioral observation on a group, which contained 38 individuals and ranged over ca. 60 ha during the study period. Two observers carried out simultaneous focal-animal sampling of adult female pairs during full-day follows using global positioning system which enabled us to quantify interindividual distances (IIDs), group members within visual range (i.e., visual unit), and separation duration beyond visual range as indicators of cohesion among individuals. We found considerable variation in spatio-temporal group cohesion. The overall mean IID was 99.9 m (range = 0-618.2 m). The percentage of IIDs within visual range was 23.1%, within auditory range was 59.8%, and beyond auditory range was 17.1%. IIDs varied with activity; they were shorter during grooming and resting, and longer during foraging and traveling. Low-ranking females showed less cohesion than high-ranking ones. Kin females stayed nearly always within audible range. The macaques were weakly cohesive with small mean visual unit size (3.15 counting only adults, 5.99 counting all individuals). Both-sex units were the most frequently observed visual unit type when they were grooming/resting. Conversely, female units were the most frequently observed visual unit type when they were foraging. The overall mean visual separation duration was 25.7 min (range = 3-513 min). Separation duration was associated with dominance rank. These results suggest that Japanese macaques regulate cohesion among individuals depending on their activity and on social relationships; they were separated to adapt food distribution and aggregated to maintain social interactions.

Relatedness and Demography of African Forest Elephants: Inferences from Noninvasive Fecal DNA Analyses

African forest elephants (Loxodonta cyclotis) are genetically and morphologically distinct from their savannah counterparts, but their biology remains poorly understood. In this study, I use noninvasive fecal DNA analyses to examine the relatedness structure and historical demography of forest elephants at 2 sites in SW Gabon, central Africa. Pairwise relatedness values calculated between 162 elephant individuals genotyped at 8 microsatellite loci were significantly higher within spatially associated dung piles than between random pairings for one site. First- and second-order relatives were most commonly detected among dung piles from adult female pairs and adult females and juveniles. Pairwise relatedness estimates suggested that, like savannah elephants, forest groups are largely composed of adult females, their sisters, and juvenile offspring. Associations between males, and groups containing juveniles from multiple related females, were detected but at much lower frequency. Analysis of mitochondrial d-loop sequences from 70 elephant individuals identified 2 haplogroups in SW Gabon.

Fine-scale genetic and social structuring in a central Appalachian white-tailed deer herd

Spatial genetic structure in white-tailed deer (Odocoileus virginianus) has been examined at regional scales, but genetic markers with the resolution to detect fine-scale patterns have appeared only recently. We used a panel of microsatellite DNA markers, radiotelemetry data, and visual observations of marked deer to study fine-scale social and genetic structure in a high-density population of white-tailed deer (12–20 deer/km2). We collected genetic data on 229 adult females, 102 of which were assigned to 28 social groups. Our results were consistent with the conceptual model of white-tailed deer social structure, where philopatric females form social groups composed of related individuals. Within-group relatedness values approached the expected value for 1st cousins (R = 0.103, SE = 0.033), but individuals among groups (R = −0.014, SE = 0.003) and overall (R = −0.009, SE = 0.003) were unrelated. Fixation indices revealed a significant departure from equilibrium values among social groups (FST = 0.076, SE = 0.007) and an excess of heterozygotes within groups (FIS = −0.050, SE = 0.018), consistent with theoretical expectations for mammal populations characterized by female philopatry and a polygynous mating system. Analyses of spatial autocorrelation indicated genetic structuring occurred at a very fine spatial scale, where pairs of adult females within 1 km were genetically nonindependent. The occurrence of fine-scale genetic and social structure has implications for the ecology and management of white-tailed deer, including habitat use and resource competition, offspring sex allocation theories, disease transmission, and the consideration of social behaviors in management.

A Potential Role for Oxytocin in the Intergenerational Transmission of Secure Attachment

If a significant amount of psychopathology stems from insecure attachment during infancy and childhood (Berant et al, 2008), then much of this illness is perpetuated by the intergenerational transmission of attachment styles (van Ijzendoorn et al, 1995). One fundamental challenge for psychiatry is to break this cycle, and doing so will require knowledge of the biological and psychosocial mechanisms that fuel it. In this issue, Strathearn and colleagues present evidence that the neuropeptide oxytocin may be an important component of this mechanism. Oxytocin mediates mother– infant attachment in rats and sheep, as well as adult female pair bond formation in prairie voles (Insel and Young, 2001); hence it is reasonable to hypothesize that it might also mediate attachment between human mothers and their children. Recently, researchers have begun investigating the role of oxytocin in human behavior through the use of intranasal oxitocin sprays that seem to enable neuropeptides to cross the blood–brain barrier (Born et al, 2002). These studies have demonstrated several remarkable behavioral effects of oxytocin in human subjects, including increased gazing to the eye region of faces, improved face expression recognition, enhanced encoding of positive social memories, decreased behavioral and neuroendocrine responses to social stress, increased positive communication between couples, and increased levels of trust and generosity in economic games (Ebstein et al, 2009; Heinrichs and Domes, 2008). Most of these studies have been conducted with male subjects, however, and human maternal behavior has not yet been targeted with this approach. In this issue, Strathearn and colleagues investigate the influence of the oxytocin system on attachment with an alternative and innovative approach that emphasizes ecological validity. During pregnancy, women were assessed for attachment styles and categorized as either Type A (insecure, dismissive attachment) or Type B (securely attached) mothers. Approximately 7 months after giving birth, the mothers’ plasma oxytocin response to an interaction with their infant was measured, and Type B mothers were found to have a greater oxytocin response than Type A mothers. Approximately 11 months after delivery, both types of mothers were imaged with fMRI, as they viewed pictures of both their own and other infants displaying happy, sad, or neutral facial expressions. Type B mothers, who had earlier exhibited the stronger oxytocin response to interactions with their infants, showed a stronger ventral striatum response to their infant’s happy and sad faces than did Type A mothers. Moreover, there was a significant positive correlation between a mother’s oxytocin response when interacting with her infant and her ventral striatum response when later viewing her infant’s face in the MRI scanner. The ventral striatum is a putative reward region at the cross-roads of the mesolimbic dopamine and oxytocin systems (Skuse and Gallagher, 2009), and both dopamine and oxytocin are known to facilitate pair bonding in female prairie voles (Young et al, 2005). Although oxytocin was not measured during the scanning session, it is possible that the higher oxytocin levels characteristic of Type B mothers render stimuli associated with their own child more rewarding than is the case for Type A mothers, and this, in turn, could very well influence the mothers’ responsiveness to her infant and hence the quality of attachment that develops. A necessary caveat to these notable findings is that the authors measured oxytocin in plasma, but plasma oxytocin may not always be an accurate reflection of oxytocin levels in the brain (Landgraf and Neumann, 2004). An important next step would be to determine whether intranasal administration of oxytocin to Type A mothers before imaging augments their ventral striatum response to viewing pictures of their own infants. Nevertheless, this Received 31 July 2009; accepted 31 July 2009 *Correspondence: Dr JK Rilling, Department of Anthropology, Psychiatry and Behavioral Sciences, Emory University, 1557 Dickey Drive, Atlanta, GA 30322, USA, Tel: + 404 727 3062, Fax: + 404 727 2860, E-mail: jrillin@emory.edu Neuropsychopharmacology (2009) 34, 2621–2622 & 2009 Nature Publishing Group All rights reserved 0893-133X/09 $32.00

シジュウカラの繁殖個体群

The breeding season of the Great Tit Parus major is divided into two periods: the early and late seasons. In the early breeding population, the number of pairs varied from 45 to 152, with an average of 102±24 SD. In comparison, the late population was smaller than the early population every year and varied from 30 to 95, with an average of 54±18 SD pairs. Half of the early breeders were adult breeders from the previous year, and most of the remaining breeders were young belonging to winter flocks in previous years. The late breeding population consisted mainly of pairs that were producing their second brood that season, and repeat breeders whose first brood had failed. The proportion of adult male and adult female pairs was higher than other pairs. Most pairs were faithful, but divorce occurred every year. The population also included some pairs that did not breed and single males. The longevity was nine years in males and seven years in females.

Abdominal odours of young, low-ranking European rabbit mothers are less attractive to pups: an experiment with animals living under natural breeding conditions

Lactating rabbit females (Oryctolagus cuniculus) emit abdominal, ventral odour cues that are involved in guiding the pups to the nipples. We tested the impact of the females’ social rank and age on the emission of this odour signal; both factors are highly collinear in wild rabbits and we did not aim to disentangle them in our study. We predicted that the abdominal odours of young, low-ranking females, which are usually more stressed and have a comparatively lower body condition, should be less attractive to pups than those of older, high-ranking females. For the experiment, we caught females from a population of wild-type European rabbits living in a large field enclosure. Pairs of adult females were placed in boxes with wire-mesh floor fixed over an arena with three rabbit pups aged 4–7 days old. First, we evaluated the effectiveness of our two-choice design by testing lactating females (LF) against non-lactating (NLF) controls (n = 17 pairs). In accordance with recent studies, the pups showed a clear preference for lactating females by means of a higher exploration time and more local searching under the ventral region of these females. In a second experiment, the pups chose between lactating 1-year-old, low-ranking females (Y/LRF) and older, high-ranking females (O/HRF) (n = 10 pairs). These latter assays suggested a comparatively lower attractiveness of Y/LRF females to pups searching for milk. Although the pups showed no significant preference in exploration behaviour, they preferably directed local searching events to the abdominal region of O/HRF females. In conclusion, our study suggests that mother–offspring chemosensory communication is modified by the mother’s age and social rank, i.e., by a complex of factors that are strongly linked in rabbit females in the wild.

Female-Biased Dispersal and Gene Flow in a Behaviorally Monogamous Mammal, the Large Treeshrew (Tupaia tana)

BackgroundFemale-biased dispersal (FBD) is predicted to occur in monogamous species due to local resource competition among females, but evidence for this association in mammals is scarce. The predicted relationship between FBD and monogamy may also be too simplistic, given that many pair-living mammals exhibit substantial extra-pair paternity.Methodology/Principal FindingsI examined whether dispersal and gene flow are female-biased in the large treeshrew (Tupaia tana) in Borneo, a behaviorally monogamous species with a genetic mating system characterized by high rates (50%) of extra-pair paternity. Genetic analyses provided evidence of FBD in this species. As predicted for FBD, I found lower mean values for the corrected assignment index for adult females than for males using seven microsatellite loci, indicating that female individuals were more likely to be immigrants. Adult female pairs were also less related than adult male pairs. Furthermore, comparison of Bayesian coalescent-based estimates of migration rates using maternally and bi-parentally inherited genetic markers suggested that gene flow is female-biased in T. tana. The effective number of migrants between populations estimated from mitochondrial DNA sequence was three times higher than the number estimated using autosomal microsatellites.Conclusions/SignificanceThese results provide the first evidence of FBD in a behaviorally monogamous species without mating fidelity. I argue that competition among females for feeding territories creates a sexual asymmetry in the costs and benefits of dispersal in treeshrews.

Day length and estradiol affect same-sex affiliative behavior in the female meadow vole

Non-sexual social bonding between adult mammals is poorly understood, despite its importance in many species. Female meadow voles are territorial and nest alone in long summer day lengths when circulating estradiol concentrations are high, but cohabit in groups in short winter photoperiods when estradiol secretion is low. The influence of day length and estradiol on same-sex huddling behavior was assessed in adult female pairs housed together in long day lengths (LDs) or short day lengths (SDs) from weaning. The behavior of intact, ovariectomized, and estradiol-treated ovariectomized females from each photoperiod was assessed during 3 h partner-preference tests. Intact SD voles, unlike intact LD voles, spent the majority of the test in proximity to their cage-mates. Estradiol treatment of SD voles significantly reduced time spent huddling with the partner. Neither ovariectomy nor estradiol treatment significantly affected the amount of time LD females spent in contact with their partners. Low estradiol availability is therefore a necessary but not sufficient condition for maintenance of high levels of huddling. These results establish that ovarian hormones interact with photoperiod to affect same-sex social behavior.

Insect gladiators II: Competitive interactions within and between bethylid parasitoid species of the coffee berry borer, Hypothenemus hampei (Coleoptera: Scolytidae)

The coffee berry borer, Hypothenemus hampei (Ferrari) (Coleoptera: Scolytidae) causes substantial reductions in coffee production. It originates from Africa but is now present in almost all of the major coffee producing countries. Classical biological control attempts around the world, including South and Central America, the Caribbean, Indian sub-continent, Indonesia, and Polynesia, including introductions of the African bethylid wasps Prorops nasuta Waterston and Cephalonomia stephanoderis Betrem, have not yet proved sufficiently successful. In Mexico, a bethylid wasp indigenous to North America and Europe, Cephalonomia hyalinipennis Ashmead, has naturally started to attack the borer. The presence of multiple species of natural enemies has the potential to disrupt biological control via negative interspecific interactions. We evaluate both inter- and intraspecific competition among these three bethylids in the laboratory, focussing on pairs of adult females competing directly for hosts. In interspecific contests, the loser is frequently killed. C. stephanoderis is the most successful species, while P. nasuta females never killed their opponents. Intraspecific interactions often involved fighting behavior but were non-fatal. We discuss the implications of the differing strengths of such inter- and intraspecific interactions for the coexistence of these natural enemies of the coffee berry borer and for biological control.

Social interactions during development in the ovoviviparous cockroach Schultesia lampyridiformis

Abstract Cockroaches are generally divided into solitary and gregarious species. Schultesia lampyridiformis (Zetoborinae) is a neotropical cockroach presenting unusual characteristics: it inhabits only pendulous nests of colonial Cacicus birds and feeds on broken eggs or bird corpses. This patchy habitat and food resource was expected to favour gregarious habits, which were effectively observed in adults. However, young nymphs dispersed during the first hours following birth. The gregarious life style should thus appear during the course of nymphal development. This study is aimed at specifying the timing of apparition of gregariousness during the development, and identifying the behaviours characterising the solitary and gregarious phases. We compared under experimental conditions social interactions and spatial distribution in pairs of nymphs at different instars (1, 2, 3, 5 and last instar) and in pairs of adult females. The gregarious phase appeared progressively in the last nymphal instars, and was characterized by a simultaneous increase in several behavioural features: length of interaction sequences, proportion of mutual antennal contacts, rate of answer to social stimulations from conspecifics and proportion of time spent close to conspecifics. This behavioural change is discussed regarding its possible function and importance for comparative studies of gregariousness.

The energetic cost of protogynous versus protandrous sex change in the bi-directional sex-changing fish Gobiodon histrio

To investigate the relative cost of protogynous versus protandrous sex change we induced sex change in each direction in Gobiodon histrio (Gobiidae) and then compared growth, body condition and biochemical condition between sex-changed and non-sex-changed fish in treatment and control groups. Sex change in each direction was induced by establishing pairs of adult males and pairs of adult females on isolated coral colonies. Heterosexual pairs were used as controls. For both males and females, growth and body condition did not vary between fish that changed sex and those that did not. The relatively low cost of sex change, compared to the likely costs of searching for a mate of the correct sex, appears to explain the evolution of bi-directional sex change in coral-dwelling gobies. Lipid concentrations in the liver of males and females that changed sex were reduced by similar amounts (34% and 41%, respectively) compared to male and female controls that did not change sex. Therefore, changes in biochemical condition were approximately equal for fish that sex change in each direction and cannot explain the unequal frequency of sex change in each direction in natural populations of G. histrio.

Intra-troop affiliative relationships of females with newborn infants in wild ring-tailed lemurs (Lemur catta).

To determine how the birth and development of infants influence their mothers' social relationships with other adult troop members, we observed two free-ranging troops of ring-tailed lemurs (Lemur catta) at the Berenty Reserve, Madagascar. The number of acts of affiliative contact that the mothers received from other adult troop members during the first and second months of infant life were significantly higher than those before they gave birth, and the values during the third month were as low as that before giving birth. Two mothers received acts of affiliative contact less frequently after their infants died, compared with the values while the infants were alive. On the other hand, more than 95% of all acts of licking of infants by adult troop members other than their mothers occurred when the infants were in contact with their mothers. These findings suggest that infants per se and mothers per se were not attractive, but rather the mother-infant pair was attractive to other troop members. Acts of infant-licking were observed in almost all mother-mother pairs and mother-non-mother adult female pairs, and in two thirds of mother-adult male pairs. Moreover, the frequency of infant-licking was not affected by female parity, female and male dominance rank, or infant sex. Therefore, acts of infant-licking, which are widespread among troop members, may function to make or maintain stable social relationships.

Genetic relatedness and home-range overlap among female black bears (Ursus americanus) in northern Ontario, Canada

The degree of philopatry exhibited by females in an unhunted black bear (Ursus americanus) population occupying the Chapleau Crown Game Preserve in northern Ontario was examined. A truncated kernel estimator was used to identify home-range use. Pairs of adult females were categorized as having home ranges that had moderate overlap or low overlap or were adjacent and non-overlapping or non-adjacent and non-overlapping. Females had low overlap with 6.4 other females, on average, and moderate overlap with 1.5 females. The degree of philopatry was assessed using two methods, each of which was used in an attempt to examine home-range overlap and average genetic relatedness. Relatedness among bears was determined from DNA fingerprints, using an alkaline phosphatase labelled multilocus probe and chemiluminescence detection. The first method involved choosing the 3 oldest females in the region to represent potential matriarchs, and all neighbouring females were identified (n = 8, 8, and 11). DNA fingerprints from each matriarch were compared with those of her neighbours. Average band-sharing coefficients and relatedness estimates within the groups did not reveal patterns of close kinship. The second method involved band-sharing comparisons among pairs of females from each of the 4 home-range categories (n = 12, 57, 80, and 21). Again, no relationship between spatial proximity and average genetic relatedness (range 0.032-0.120) was suggested. The extensive home-range overlap exhibited by this population is not a consequence of natal philopatric tendencies.

Systematic identification of twins by computerised searches of NHS patient registers in the UK.

OBJECTIVES: This study aimed to assess the feasibility, sensitivity, and specificity of a systematic search of the NHS central register for twins of the same sex. DESIGN, SETTING, AND SUBJECTS:...

Use of Nest Trees by the Mountain Brushtail Possum (Trichosurus caninus) (Phalangeridae : Marsupialia). III. Spatial Configuration and Co-occupancy of Nest Trees

Radio-tracking was used to examine the spatial configuration and co-occupancy of large trees with hollows occupied by 16 mountain brushtail possums (Trichosurus caninus) at Cambarville in the central highlands of Victoria, south-eastern Australia. The distance that animals moved between trees on successive days was also examined. Our analyses showed that animals often remained in a given den tree on successive days. On nights when animals did shift between den sites, they typically moved to a new tree that was relatively nearby (< 200 m). Long-distance movements (e.g. > 300 m) between den trees were rare. Considerable variation was found between individuals in the size of areas encompassing trees used frequently (≥5 times) (‘core denning range’) and those encompassing all occupied trees [i.e. including those used infrequently (< 5 times)] (‘total denning range’). The mean area of the core denning range averaged about 1·1 ha for males and 0·7 ha for females. The mean value for the total denning range was approximately 2·6 ha for males and females respectively. Considerable overlap was found in the total denning ranges of pairs of adult males and pairs of adult females. For most animals, the total denning range was shared with the total denning ranges of several other animals. There was substantial variation in the extent of this overlap, ranging from complete enclosure to the sharing of a single tree. The extent of overlap was more limited for the core denning ranges, particularly among females. We observed differences in the extent of the overlap of the total denning ranges of pairs of males and pairs of females in the breeding season (January–March) and non-breeding season (the remaining months of the year). Fewer instances of overlapping total denning ranges among pairs of both males and females were found during the breeding season. The total denning ranges in the breeding season were generally smaller than those in the non- breeding season. Simultaneous co-occupancy of a given den tree by T. caninus was relatively common. Unexpectedly, there was a number of instances of groups of three or four adult animals sharing the same den site on the same night. We recorded several instances of sharing by pairs of animals of the same sex, especially adult males. However, most records of simultaneous tree use were by an adult male and an adult female T. caninus. The extent of overlap in the denning ranges of animals and the prevalence of simultaneous co-occupancy of den trees indicate that the social behaviour of T. caninus at Cambarville may be different from that observed among populations of the species elsewhere in Australia. Possible reasons for these differences are outlined.

Golden‐bellied mangabeys (Cercocebus galeritus chrysogaster) at the Sacramento Zoo: Adult heterosexual pairs

AbstractThe behaviors of three different adult male–adult female pairs of golden‐bellied mangabeys (Cercocebus galeritus chrysogaster) were compared. Correlates of restricted social conditions and of the presence of offspring on adult behavior and direction of aggressive behaviors were noted. A captive pair displayed self‐biting and other aberrant behaviors, a lone wild‐caught pair showed redirected aggression related to sex, and a pair housed with its offspring showed close social proximity and protection of an infant. The implications of housing and experience for space and visitor exposure are discussed. Observer‐ vs. visitor‐directed displays are seen as important measures of group and visitor effects.

Spring Arrival Times and Assortative Mating of Kestrels in South Scotland

(1) In a partially migrant population of kestrels studied for 4 years in south Scotland, migrants settled in spring from late February until late April. Mean arrival time was earlier following a mild winter, but was not related to local food supply, so that the mean length of courtship (pairing to egg-laying) was longer in a poor vole year (when laying was late) than in good times (when laying was early). (2) Within years, migrants that arrived early tended to pair earlier, and lay earlier, than those that arrived late. Later pairing birds partly compensated for this by having shorter courtship than those that paired early. (3) Males and females arrived over roughly the same period and there was no difference in their mean arrival dates. However, within pairs, the males arrived about 4 days, on average before their females. The sex ratio of winter residents was biased towards males, so more early arriving females than males were able to pair with residents on arrival. This resulted in a surplus of unpaired males that persisted until the end of the settling period when all breeding birds were paired. (4) In the 2 years when they bred in substantial numbers, first-year birds arrived later than adults. In males, but not females, first-year birds resident over winter waited longer than adults before finding a mate. (5) Selective mating of first-year birds and adults occurred in 1978 but not 1979. The observed preponderance of yearling-yearling and adult-adult pairs in 1978 seemed largely due to the different arrival times of the two age groups, though this did not entirely explain the infrequency of yearling-male x adult-female pairs compared with adult-male x yearling-female. The data were consistent with the idea that females, but not males, preferred adult partners when these were available.

Black-white differences in plasma lipids and lipoproteins in adults: The Cincinnati lipid research clinic population study

Black—white lipoprotein differences were studied in 43 pairs of adult males and 51 pairs of adult females to test the hypothesis that in a heterogeneous suburban biethnic setting, blacks have higher levels of high density lipoprotein cholesterol (C-HDL), lower levels of low density lipoprotein cholesterol (C-LDL), and lower levels of triglyceride (TG) when pair-matched by total plasma cholesterol, age, and sex with whites. With essentially identical total plasma cholesterol levels and comparable degrees of ponderosity, black males had lower plasma TG ( P < 0.05) and higher plasma C-HDL levels ( P < 0.005). There were no significant male black—white differences in C-LDL, but the ratio of C-LDL to C-HDL was lower in black males ( P < 0.01). There were no significant differences in any lipoprotein fractions or the C-LDL/C-HDL ratio between black and white females, although black females had slightly lower plasma TG and slightly higher C-HDL than white females.