鳄蜥对熟悉和陌生个体气味的辨别

个体辨别对于减少同种争斗以及配偶选择具有重要意义。我们用棉棒粘取鳄蜥(Shinisaurus crocodilurus)尿液作为气味源,以香水作为对照,测定鳄蜥对熟悉个体气味、陌生个体气味以及香水的舔舌次数和舔舌潜伏期,来探讨鳄蜥通过化学信息辨别熟悉和陌生个体的能力。结果显示,不论是雌性还是雄性,对不同个体尿液的舔舌次数均显著高于对香水的,舔舌潜伏期显著短于香水的;尽管雄性对陌生同性个体气味与熟悉同性个体气味的舔舌次数无显著差异,但对前者的舔舌潜伏期显著短于后者;雄性对陌生雌性气味的舔舌次数显著多于熟悉雌性气味的,对前者的舔舌潜伏期显著短于后者;雌性对陌生雄性气味的舔舌潜伏期显著短于对熟悉雄性气味的;雄鳄蜥对陌生雌性气味的舔舌次数显著多于雌鳄蜥对陌生雄性的。结果表明,鳄蜥能辨别同种个体的化学信息,并能通过化学信息来辨别熟悉和陌生个体,推测鳄蜥的这种辨别能力对其领域分配以及繁殖交配有重要作用。     

Behavioural development of conspecific odour preferences in bank voles,Clethrionomys glareolus

Biological odours of conspecifics are known to have strong influences on behavioural interaction in bank voles Clethrionomys glareolus. This experiment tested two hypotheses. (1) Olfactory cues from familiar and unfamiliar mature opposite-sex conspecifics differ in their attractiveness to males and females, and their behavioural reactions change with age. (2) A genetically based mechanism is involved in female recognition of kin.In a two-choice preference test, prepubertal males and females were more attracted to familiar than to unfamiliar odours of opposite-sex conspecifics, as manifested by more time spent sniffing familiar voles. As the young reached sexual maturity they shifted their odour preferences. Mature males and females preferred the novel odour of unrelated opposite-sex conspecifics to that of relatives. The results of experiments testing the second hypothesis indicate that females use a genetically based mechanism to recognise their kin. Young and mature females were able to recognise the odour of their biological but socially unknown fathers, and showed the same pattern of behaviour as females in previous experiments.The possible biological functions of kin recognition in bank voles are discussed.     

Odour-genes eovariance and differential investigation of individual odours in the Mus species complex

Previous research using habituation techniques has demonstrated that greater genetic similarity between two individuals is associated with more similarity in the qualities of their individual odours ('odour-genes eovariance'). We assessed odour similarities across species in two pairs of genetically close species within the Mus species complex (M. musculus and M. domesticus; M. spicilegus and M. macedonicus). Subjects treated odours within each species pair as similar compared with an odour from the other species pair. Subjects also treated odours of M. spicilegus males from the same population as similar compared with the odour of M. spicilegus males from a different population. This confirms odour-genes eovariance across species and within populations and also supports previous findings that odour similarities are more salient than specific odour markers. When adult males were presented with odours of females from two different heterospecific species, subjects spent more time investigating the odour from his own species pair than the other species pair, indicating greater interest in the odour of the closer heterospecific and demonstrating that odour-genes eovariance is reflected in behavioural responses to odours. Implications of odour-genes eovariance as a basis for identifying degrees of genetic relatedness of unfamiliar individuals through similarities in individual odours are discussed.     

雌性布氏田鼠对雄鼠气味的辨别

通过雌性布氏田导其配偶和陌生雄鼠气味的辨别实验,以及无交配经历的成年雌鼠对社会等级不同的陌生雄鼠气的辨别实验发现,有生育经历的雌鼠对陌生雄鼠气味的探究行为明显多于对配偶气味的控究,但雌鼠在配偶雄鼠气味周围的停留时间、自身修饰行为和何处行为的发生频次和持续地陌生雄鼠,没有交配经历的雌鼠对处于从鼠地位的雄性个体气味探究行为多于对优势雄性的控究,而其他行为表现没有明显差异。表明,雌性布氏田鼠可以利用气味     

Retention of social recognition after hibernation in Belding's ground squirrels

The retention of social memory during long periods of separation, such as hibernation or migration, has not been well documented, despite evidence for long-term social relationships in migrating species or in long-lived sedentary species. We investigated the ability of captive Belding's ground squirrels, Spermophilus beldingi, to remember previously familiar individuals as well as littermates after 9 months of isolation. Before hibernation, young ground squirrels discriminated between odours of familiar and unfamiliar individuals, as shown by greater investigation of a novel individual's odour. The following spring, these yearlings did not respond differentially to odours of previously familiar and unfamiliar individuals, suggesting that memory for familiar conspecifics was lost during hibernation. In contrast, both female and male yearlings continued to discriminate between odours of littermates and previously familiar nonlittermates. Thus, recognition of close kin was maintained during prolonged social isolation, but recognition of familiar, unrelated individuals was not. If re-establishment of familiarity is not costly or if adults rarely interact with the same individuals in successive years, then selection may not favour retention of individual memories of particular conspecifics over the winter. Even though males rarely encounter kin after dispersal, yearling males did recognize their siblings, suggesting that the relative costs of maintaining kin-recognition abilities year-round may be low. Possible mechanisms underlying the formation and maintenance of individual and kin recognition are discussed. Copyright 2000 The Association for the Study of Animal Behaviour.     

Genetic relatedness assessment through individual odour similarities in mice

Previous research has demonstrated that closer genetic relatedness between individuals (from kin to across species) is associated with greater similarity in the qualities of their individual odours ('odour-genes covariance'). This predictable relationship between individual genotypes and individual odours could enable animals to assess their degree of genetic relatedness to other individuals by comparing the degree of similarity between another individual's odour and their own odour. In two-choice tests with odours of unfamiliar mice from different populations and species, subjects from two species of wild mice, Mus spicilegus and M. musculus , that had been raised in mixed litters of both species spent significantly more time investigating the ano-genital odour of the more genetically similar individual. This differential interest was not affected by common rearing with heterospecifics. These responses are consistent with a self-referencing mechanism enabling differential responses across a wide spectrum of genetic relatedness from kin through populations to heterospecifics. These assessments depend on the degree of similarity between the donor's and the subject's odours rather than on differences between them. Such a parsimonious mechanism may provide a basis for differential responses to conspecifics as opposed to heterospecifics that may function as a premating isolating mechanism.  © 2003 The Linnean Society of London, Biological Journal of the Linnean Society , 2003, 78, 595–603.     

Preferences of newborn mice for odours indicating closer genetic relatedness: is experience necessary?

Evidence from studies with adult rodents indicates that individual recognition enables distinctions between familiar individuals irrespective of relatedness (but including close kin) and a separate mechanism enables discriminations based on genetic relatedness without prior familiarity. For example, adult mice could assess the extent of their genetic relatedness to unfamiliar individuals using perceptual similarities between their individual odours. The ontogeny of this genetic relatedness assessment mechanism, however, had not been investigated. Here, in two-choice tests, newborn mice differentially preferred odours of more genetically similar lactating females (paternal aunts to unrelated conspecific and conspecific to heterospecific) even without prior direct exposure to adults with the tested genotypes. The results provide a direct demonstration of genetic relatedness assessment abilities in newborns and show that experience with parental odours is not necessary for genetic relatedness distinctions. Future studies will be necessary to determine whether exposure to odours of other foetuses in the womb or littermates shortly after birth affects this genetic relatedness assessment process.     

Individual Odours in Two Chromosomal Species of Blind,Subterranean Mole Rat (Spalax ehrenbergi): Conspecific and Cross-species Discrimination

Mole rats from two chromosomal species (2n = 58 and 2n = 60) of the Spalax ehrenbergi superspecies of Israel were tested to determine whether they were able to discriminate differences in the odour of urine from same-sex individuals of their own and of the other chromosomal species. An habituation-discrimination apparatus was designed for use with these solitary and blind subterranean rodents. Animals habituated to the odour of urine from one individual presented for 10 min at a centre sniffing area in the roof of a 50 cm long Perspex tunnel. The odour of urine from the original donor and from a second individual were presented at two other sniffing areas in the tunnel roof during a 5 min discrimination phase. Significant differences in the time spent investigating the two odours demonstrated successful discrimination between them. The results indicate that male and female mole rats of both species can discriminate between the individual-specific odour cues in urine from pairs of conspecifics and pairs of heterospecific mole rats.     

Olfactory communication and the importance of different odour sources in the ferret (Mustela putorius f. furo)

Olfactory communication has a major role in solitary carnivores, particularly during the breeding season. Scent-marking behaviour in ferret (Mustela putorius f. furo) has been well studied, but not the significance of the deposited odours for the animal. We compared the interest in urogenital, anal and body odours of opposite-sex conspecifics between male and female ferrets and investigated both sexes’ discrimination ability (familiar vs. unfamiliar) for these three opposite-sex odours and the use of its ability by females during the breeding season. Males are more interested than females in the urogenital odour of the opposite sex. Male body odour probably did not interest females and males are somewhat interested in the female one. However, anal odour of the opposite sex is as interesting for males as for females and both sexes are able to discriminate familiar anal odour from an unfamiliar one. Moreover, females could use this ability when they must choose to have some sensory contact between olfactory familiar and unfamiliar males since they prefer to be in contact with the former. These results are coherent with behavioural differences observed between male and female solitary mustelids in the field and in captivity, and the consortship success of resident males compared to roaming males.     

Reliability of odour–genes covariance despite diet changes: a test in mound‐building mice

Odour–genes covariance (i.e. that individual odour similarities covary with genetic similarity) allows animals to assess their genetic relatedness to one another by comparing the similarities between their individual odours. The reliability of the odour–gene covariance phenomenon under environmental changes has not yet been explored. Using an innovative habituation‐generalization procedure, we tested whether the modifications of body odours induced by a change in diet interfered with the perceived similarity of individual odours of more genetically similar individuals. The effects of a change in diet, by adding aniseed flavour to the drinking water, was assessed in male mound‐building mice, a species in which odour–genes covariance has already been demonstrated. The results obtained indicate that mice perceive more similarities in the odours of sibling males than in those of nonrelatives, despite the effects of diet on body odours. We suggest that the reliability of signals arising from odour–genes covariance is likely a result of the independence between traits indicating genetic relatedness and indicator signals of biological states (e.g. diet) in body odours. © 2012 The Linnean Society of London, Biological Journal of the Linnean Society, 2012, 106 , 682–688.     

Size-Dependent Chemosensory Responses to Familiar and Unfamiliar Conspecific Faecal Pellets by the Iberian Rock-Lizard, Lacerta monticola

We conducted a field study to analyse the social relationships between males of the Iberian rock lizard (Lacerta monticola). The degree of familiarity was determined based on the degree of overlap between their home ranges. We then designed a laboratory experiment to test whether the same males were able to discriminate between familiar and unfamiliar conspecifics using faecal pellet odours. Differential tongue‐flick rates suggest that large males (snout‐to‐vent length, SVL > 75 mm), at least, may discriminate between odours of familiar and unfamiliar males. The behavioural responses were dependent on relative differences in body size between the responding male and the male that donated the faecal pellet. Thus, as responding small males increased in size relative to their corresponding familiar male, their rate of tongue‐flicking significantly decreased; this was not the case in response to unfamiliar males. In contrast, there were no significant correlations between the response of large males to familiar or unfamiliar male stimuli, regardless of size differences. These results suggest that chemical cues contained in faecal pellets allow individual recognition in male L. monticola, and that the response depends on body size. We suggest that faecal pellets might be used to scent‐mark home ranges, which would contribute to lowering the costs of aggressive interactions.     

Olfactory cues in discrimination among individuals in dominance hierarchies in the cockroach, Nauphoeta cinerea

ABSTRACT. The purpose of this study was to explore the olfactory recognition mechanisms used by individual subordinate male cockroaches, Nauphoeta cinerea (Olivier), in a dominance hierarchy. Results of two independent sets of experiments, one using an olfactometer and the other using an arena, suggest that olfactory cues are important to males. Subordinate males did not avoid dominant male odour in an olfactometer but could discriminate between the odours of familiar and unfamiliar individual dominant males, preferring the odour of the dominant male with which they had previous social contact. Since test subordinates did not avoid dominant male odours in the olfactometer, it is possible that the distance an individual remains from a dominant is important. To test this, individual dominant and subordinate males were tethered in the centre of an arena. Subordinate males were introduced into the arena and allowed to approach the tethered male. They approached tethered dominants and subordinates differently, and tended to keep away from the dominants. Tethered males unfamiliar to the test animals were avoided as well.     

Right-nostril dominance in discrimination of unfamiliar, but not familiar, odours

In a recent PET study on processing of unfamiliar odours we observed that odour discrimination performance was superior during right compared with left nostril presentations, and that mainly the right cerebral hemisphere was activated. In the present study we investigated whether the asymmetric performance is present also during the processing of familiar odours. Seventy-one right-handed healthy subjects (age 21-49 years, 40 females) with normal nasal anatomy and olfactory thresholds participated. Forty pairs of odours (20 familiar and 20 unfamiliar) were presented in the same/different paradigm, alternating nostrils and balancing the order. The number of errors during the discrimination task was compared with respect to nostril and odour familiarity. The overall odour discrimination performance was superior on the right side. However, this difference was valid only for unfamiliar odours, whereas the performance for familiar odours was symmetrical. Familiar odours were easier to discriminate than unfamiliar ones. The present data are congruent with the idea of a semantic influence on odour processing. Odours seem to be processed with a right sided preponderance when not clearly familiar, and symmetrically when language becomes involved. Future studies on odour processing should therefore take into account odour familiarity and side of presentation.     

Reproduction strategy in an island population of yellow-necked mice

A population of yellow-necked mice, Apodemus flavicollis, inhabiting Crabapple Island (NE Poland) was sampled from 1994–2002. The catch-mark-release method was applied. Sexually mature males and females (including pregnant ones) as well as immatures of each sex were identified. During the study period 3,036 mice were caught 10,672 times. The number of mice caught varied from 6 individuals (April 1999) to 272 (July 1996). The number of both mature females and mature males increased linearly with population size. Differences in the reproductive strategies of yellow-necked mouse and bank voles, Clethrionomys glareolus, are discussed. The respective strategies led to high variability in the population size of mice and much less variability in the case of the voles during the breeding season.     

Olfactory Discrimination of Individual Scents in the Subterranean Rodent Ctenomys talarum (tuco-tuco)

Biological odours that convey cues regarding individual identity can provide valuable information mediating many aspects of mammalian social relationships such us dominance hierarchies, group memberships, territorial and mating activities. The ability of the subterranean rodent, tuco‐tuco (Ctenomys talarum), to discriminate between soiled shavings, urine and faeces from different individuals was investigated using the habituation–discrimination paradigm. Discrimination by both males and females was tested using scents obtained from same‐ and opposite‐sex individuals. Each test subject was habituated for three consecutive days to odour samples from the same individual; on the fourth day a scent from a novel individual was provided. For all odour sources, animals spent significantly less time investigating the habituation scent over successive trials, indicating that animals perceived the stimulus as familiar. For all stimuli, test subjects spent more time investigating the novel odour, rather than the familiar one. Animals spent more time investigating soiled shavings than urine or faeces. Both males and females discriminated novel from familiar odours in shavings and urine regardless of the gender of the odour donors. In contrast, test animals discriminated between familiar and novel odours in feces only when the fecal donors were of different sex from subjects. Possible territorial and reproductive functions of individual scent discrimination are discussed.     

Discrimination of individual odours by hamsters (Mesocricetus auratus) varies with the location of those odours

When animals perceive social signals, information about the identity and the location of the signaller can be important determinants of a response by the perceiver. An unfamiliar individual often elicits a greater response than does a familiar individual. Similarly, a signal from an unexpected location may elicit a greater response than if it came from an expected location. For example, in field experiments on vocal communication in birds, an unexpected location has been many metres away from the expected one. Laboratory experiments on the responses of voles and hamsters to scent overmarks and on the habituation of hamsters to social scents suggest that much smaller differences in the location of odours may be salient. To explore this further, we examined the influence of changes in spatial location of familiar and novel male scents on responses of female golden hamsters,M. auratus . The spatial changes were about 9 cm, less than three-fourths of the body length of our subjects. The decline in females' investigation of the same male's flank odour across four habituation trials was not affected by changing the location of the odour. During test trials, however, changes in location did influence the results. The expected higher level of investigation of a novel scent versus that of a familiar one was observed primarily when the novel scent occupied a novel location. Such increases in investigation were usually not seen when only one of these variables was changed (individual or location). Thus, small changes in spatial location influence the salience of conspecific odours in this species. Copyright 2002 The Association for the Study of Animal Behaviour. Published by Elsevier Science Ltd. All rights reserved.     

Nestling tree swallows (Tachycineta bicolor) alter begging behaviour in response to odour of familiar adults,but not their nests

Communication using chemical cues is important for many taxa, including birds, but the use of olfaction for intraspecific communication has been investigated only recently in passerines and is understudied in nestlings. To address this knowledge gap, we explored whether nestling tree swallows (Tachycineta bicolor) would recognize and respond to chemical cues of conspecifics, specifically testing begging responses to familiar and unfamiliar nest and adult odours. For the nest odour experiment, nests were treated with either orange essential oil or distilled water to create scented and unscented (control) odour environments, respectively. For the adult odour experiment, adults attending the nestlings were considered “familiar adults” and adults attending a different brood in the population were considered “unfamiliar adults.” We found that begging responses of nestlings did not differ in response to orange oil odour or water, but nestlings begged significantly longer and more intensely in response to odours of a familiar than an unfamiliar adult, regardless of adult sex. This provides evidence that tree swallows use chemical cues to alter their behaviour and opens up many exciting avenues of future research.     

Behavioural development of conspecific odour preferences in Brandt’s voleMicrotus brandti

The behavioural development of conspecific odour preferences in Brandt’s voleMicrotus brandti (Radde, 1861) was evaluated in laboratory tests. During the weaning period (15th-30th day after the birth), the preference of pups to individual odours of their parents, novel adult males and females were examined. Pups investigated odours of unfamiliar adults significantly more than those of their parents and they displayed significantly more jumping and upward visual investigating behaviours on the bedding soiled by unfamiliar adults than they did on the bedding of their parents. However, the frequency of crossing the parent’s bedding was significantly higher than the frequency of crossing the bedding of alien adults. It is suggested that odour discrimination ability was associated with the age of pups. The Brandt’s vole pups might keep themselves away from unfamiliar environments by keeping away from the novel conspecific odours.     

Behaviour of cyclic bank voles under risk of mustelid predation: do females avoid copulations?

Mustelid odours have been shown to suppress breeding in captive bank voles (Clethrionomys glareolus) from cyclic populations (Ylönen 1989; Ylönen and Ronkainen 1994). The mechanism behind the suppression is unknown. Based on a series of behavioural trials and breeding experiments with pairs of bank voles in breeding condition, we suggest that the primary cause for breeding suppression is a change in female mating behaviour. Experimental female-male pairs (n=34) exposed to mustelid odour decreased their general activity compared to control pairs (n=34). When encountering males in behavioural trials, females exposed to stoat odour were more aggressive and actively avoided precopulatory behaviours of males. No copulations were observed in experimental pairs compared to five in control pairs during the behavioural trials. Males actively approached females in general but male behaviour did not change under exposure to mustelid odours. We suggest that females are more vulnerable to mustelid predators than males and therefore actively avoid copulations in the (indirect) presence of mustelids. As well as this behavioural response, internal abortive mechanisms (cf. Bruce 1959) could play a role in the observed breeding suppression.     

Selection of odorants for memory tests on the basis of familiarity,perceived complexity,pleasantness, similarity and identification

In a procedure for the selection of two equivalent sets of familiar and two equivalent sets of unfamiliar odours for use in odour memory studies, 24 na?ve subjects were first asked to rate the familiarity, perceived complexity and pleasantness of 54 a priori unfamiliar odours and 57 a priori familiar odours and to identify the latter. After selection of the 40 most familiar and the 40 least familiar odours, the subjects sorted each of these two sets into groups of similar odours. Their results were analysed by multidimensional scaling and cluster analysis and each set was divided into two recognition sets that had the same degree of similarity between target and distractor odours and that had similar values of familiarity, pleasantness, perceived complexity (familiar and unfamiliar sets) and identifiability (familiar sets). Finally, recognition tasks were performed in order to check the equivalence in memory performance of both the two familiar and the two unfamiliar recognition sets.