Chem. Senses 26: 449-458,
2001
© Oxford University Press 2001
Female Marmoset Monkeys (Callithrix jacchus) Can Be Identified from the Chemical Composition of their Scent Marks
1 School of Biology and Biochemistry, Queen’s University of Belfast, Medical Biology Centre, Belfast, UK, 2 The Biomedical Mass Spectrometry Facility, Department of Biochemistry and Molecular Biology, Mayo Clinic, Rochester, MN 55905, USA, 3 Dalgety Food Technology Centre, Dalgety plc, Station Road, Cambridge, UK and 4 Wisconsin Regional Primate Research Center and Department of Obstetrics and Gynecology, University of Wisconsin, Madison, WI 53715, USA
Correspondence to be sent to: Tessa E. Smith, School of Biology and Biochemistry, Queen’s University of Belfast, Medical Biology Centre, Belfast BT9 7BL, UK. e-mail: t.smith{at}qub.ac.uk
 |
Abstract |
|---|
 Top Abstract IntroductionMaterials and methodsResultsDiscussionReferences |
|---|
The present study analyzed 42 organic solvent extracts of scent mark pools from five dominant female common marmosets by gas chromatography (GC) and combined GC and mass spectrometry. We determined whether there were qualitative or quantitative differences between the chemical composition of scent marks from individual females. Gas chromatography and mass spectral analysis detected the same 162 chemicals in 86% (36/42) of scent mark pools from five dominant females. This near identical chemical composition of scent marks suggested there were few, if any, qualitative differences between the chemical composition of scent marks from individual females. Instead, quantitative differences in scent may provide the key factor distinguishing individual females. Using the relative concentration of highly volatile chemicals detected by GC in scent marks, linear discriminant analysis classified scent mark pools to their correct donor
91% of the time. Such highly reliable statistical matching of scent to donor suggested that each individual female common marmoset has a unique ratio of highly volatile chemicals in their scent marks which may permit individual identification of females from odors in their scent alone. |
Introduction |
|---|
|
TopAbstractIntroductionMaterials and methodsResultsDiscussionReferences |
|---|
Chemical signaling of individual identity is widespread among solitary and social species (Halpin, 1986
). Individual chemical signatures are communicated by many scent sources, including urine [squirrel monkey, Saimiri sciureus (Laska and Hudson, 1995)], feces [rabbit, Oryctolagus cuniculus (Mykytowycz, 1973)], vaginal secretions [golden hamster, Mesocricetus auratus (Johnston et al., 1993)], secretions from specialized glands [ring tailed lemur, Lemur catta (Dugmore and Evans, 1990)] or general body odors [virginia opossum, Didelphis viriniana (Holmes, 1992)]. Odors specific to individuals are important in mammals for regulating social interactions in several contexts, including mate recognition (prairie vole, Microtus ochrogaster), mate choice (brown lemming, Lemmus trimucronatus), reproductive success (golden hamster), mother–infant relationships (virginia opossum) and territorial defense [mouse, Mus musculus (Coopersmith and Banks, 1983; Newman and Tang-Halpin, 1988; Gosling and McKay, 1990; Holmes, 1992; Tang-Martinez et al., 1993)]. In at least one species, the common marmoset, odor cues specific to certain individuals may regulate the reproductive physiology of conspecifics (Barrett et al., 1990, 1993; Smith and Abbott, 1995; Abbott et al., 1997). The present study chemically analyzed scent marks from female common marmosets to assess quantitative and/or qualitative differences between scent marks that may distinguish individual females.
The callitrichids (marmosets and tamarins) are small, arboreal, social primates that live in extended family groups in the neotropics (Rylands, 1993). Marmosets have a well-developed odor communication system with behavioral and morphological adaptations to effect efficient deposition and reception of scent material (Epple et al., 1993). Both male and female common marmosets possess specialized glandular areas in the ano-genital region comprised of large sebaceous and apocrine glands in the external skin of the genitalia (circumgenital gland) (Sutcliffe and Poole, 1978). Marmosets mix secretions from the ano-genital glands with secretions from non-specialized circumanal skin glands, a few drops of urine and possibly feces and genital discharge on the substratum to form a circumgenital scent mark (Sutcliffe and Poole, 1978). The frequency of scent marking in common marmosets is significantly modified by social and physiological context, in addition to environmental features (Epple, 1970; Sutcliffe and Poole, 1978; Epple et al., 1993; Smith and Abbott, 1998; Lazaro-Perea et al., 1999). Chemicals in the marmoset circumgenital scent mark have been implicated as playing major roles in regulating social interactions.
We have previously used behavioral bioassays to demonstrate that circumgenital scent marks (and organic solvent extracts of these scent marks) from female common marmosets contain chemical cues permitting discrimination between familiar and unfamiliar conspecifics (Smith et al., 1997). These results provided indirect evidence for the existence of individual odor signatures in common marmosets. The chemical signaling of individuality may be important to marmosets in several contexts, including regulating reproductive physiology, mother–infant recognition, territory defense and maintenance of social dominance hierarchies (Epple et al., 1993; Abbott et al., 1997). To obtain direct evidence of whether qualitative and/or quantitative differences between the chemical composition of scent marks from individual females would enable individual discrimination, we analyzed 42 organic solvent extracts of scent mark pools from five individual females by gas chromatography (GC) and combined GC and mass spectrometry (GCMS).
|
Materials and methods |
|---|
|
TopAbstractIntroductionMaterials and methodsResultsDiscussionReferences |
|---|
Subjects
Scent marks for chemical analysis were provided by five adult female common marmosets (Callithrix jacchus) that had held dominant status (rank 1) for at least 6 months prior to the study. The females were housed either as female pairs (n = 1, one dominant, one subordinate) or as trios (n = 4) of two females (one dominant, one subordinate) and a male. The marmosets used in this study were captive born and were housed at the Institute of Zoology, London [see Abbott et al. for details of animal husbandry (Abbott et al., 1988)].
Determination of female rank
Details of social group formation are provided by Abbott and Barrett et al. (Abbott, 1984; Barrett et al., 1990). Briefly, social groups were formed by placing between two and four unrelated females and between two and four unrelated males in a large observation room (2.9 x 2.2 x 1.7 m) and allowing the animals to form intra-sex behavioral dominance hierarchies. Behavioral observations were made daily on each group, for 45 min between 0900 and 1000 and 45 min between 1600 and 1700 for the first 10 days following group formation. All submissive and dominant behavioral interactions were recorded [excluding interactions involving feeding and drinking (Abbott, 1984)] and dominance matrices were constructed. A dominance hierarchy was established within each sex 3 days following group formation. Among females the hierarchy comprised a dominant female (rank 1) and one or two subordinate females (rank 2 and below). The most dominant individual (rank 1) received least aggression and most submission and the subordinate individuals received most aggression and least submission. Once the group was established it was transferred to a home cage (100 x 50 x 75 cm) and given access to an exercise cage (2 x 1 x 2 m) every 5–7 days. The sizes of social groups used in the current study (two or three animals in each) were reduced from their original sizes (between four and eight animals) because marmosets had been removed for use in additional research studies.
Determination of ovulatory function
Frequently only dominant females ovulate in social groups of common marmosets (Abbott et al., 1988). To standardize the ovarian hormone environment during odor collection circumgenital scent marks were collected from dominant females exclusively during the luteal phase of the ovarian cycle, when plasma progesterone concentrations commonly exceed 50 ng/ml. Ovulatory function was confirmed from concentrations of plasma bioactive luteinizing hormone (bLH) and progesterone in twice weekly blood samples. Ovulation (±1 day) can be reliably estimated as the day prior to plasma progesterone concentrations exceeding 10 ng/ml (Harlow et al., 1983). Methods pertaining to blood sampling in common marmosets and the measurement of concentrations of plasma bLH and progesterone were described previously by Abbott et al. (Abbott et al., 1988).
Collection of circumgenital scent marks
The technique and collection-device used for scent mark collection were previously described by Smith et al. (Smith et al., 1997). Briefly, marmosets were trained, using positive reinforcement techniques, to circumgenitally scent mark an apparatus designed for collecting scent marks [see Smith et al. for details of the procedures used to train marmosets to scent mark (Smith et al., 1997)]. Marmosets deposited scent marks on frosted Pyrex tubes (7.5 x 1 cm) that lay in an aluminum foil lined groove running the length of a wooden perch (48 cm long, 4 cm diameter). The foil minimized contamination of the Pyrex collection tubes by the wooden perch. The frosted collection tubes had a well, 0.5 cm deep, that ran along half the length of the tube. It was intended that the well would mimic the feeding sites that marmosets typically mark as well as aiding the collection of drops of urine deposited as part of the scent mark (Coimbra-Filho and Mittermeier, 1976, 1978; Sutcliffe and Poole, 1978). The wooden perch fitted with collection tubes was designed to be attached inside the home cage of the scent donor in place of the regular wooden perch that was normally positioned in the cage. The equipment used to collect and process the scent material was thoroughly cleaned prior to use and stored in an airtight, foil lined plastic container for a maximum of 24 h prior to use [see Smith et al. for details of the procedures used to clean the equipment (Smith et al., 1997)].
Pooled samples of 15 circumgenital scent marks were collected from each of the five subject females, approximately once per 2–3 weeks (coincident with the luteal phase of the ovarian cycle), over a 22 week period. All scent marks were collected between 0700 and 0900 and a pool of 15 scent marks was usually collected from an individual female within 10 min. Between five and 10 scent mark pools were collected from each female marmoset (a total of 42 scent mark pools). Scent marks were not collected if females were under veterinary supervision.
Preparation of scent material for chemical analysis
Methods used to prepare scent material for chemical analysis were modified from protocols established by previous authors to chemically analyze scent material from callitrichid primates (Yarger et al., 1977; Belcher et al., 1988). Each pooled sample in the current study contained 15 scent marks from one individual. Scent marks were collected when a scent collection tube was marked once, or at most twice (on occasion marmosets would mark the same tube twice in quick succession). The marked collection tube was removed from the foil lined groove in the wooden perch using clean forceps and dropped into a glass test tube (16 x 2 cm) containing 2 ml extraction solvent (1:3 v/v methanol: dichloromethane mix). A clean Pyrex collection tube was put in the wooden perch in place of the removed tube for further scent collection. The test tube containing extraction solvent mix and scent marked collection tube was vortexed gently for 1 min. The collection tube was removed from the test tube using a clean glass rod, discarded and the process repeated until 15 circumgenital scent marks from an individual donor had been extracted into the solvent mix. The 2 ml volume of solvent-extracted scent mark was reduced to 20 µl under a stream of nitrogen in a filtered hood and 10 µl of methanol were added. The 30 µl volume was stored at –20°C under nitrogen for a maximum of 1 month until chemical analysis.
Control samples
A control sample (total n = 20) was obtained approximately once per week over the 22 week study period (control samples were not collected during weeks 5 or 16 of the study). To prepare a control sample the complete collection device (i.e. wooden perch fitted with frosted Pyrex tubes) was placed in a soiled marmoset cage from which all animals had been removed 5 min previously. At regular intervals over a 10 min period (approximately the time taken to collect a pool of 15 scent marks) a collection tube was removed from the wooden perch and extracted in 2 ml of extraction solvent. A clean collection tube replaced the removed tube. This process was repeated until 15 tubes had been removed from the wooden perch and placed in the extraction medium. The 2 ml control solvent volume was treated as described above for a scent mark solvent extract.
GC and combined GCMS analysis
Chemical analysis was performed on a 5890 gas chromatograph (Hewlett Packard) fitted with a flame ionization detector (FID) and a WCOT OV351 column (dimensions 30 m x 0.32 mm, with a film thickness of 0.15 µm) (Phase Sep, UK). A sample volume of 2 µl was injected onto the column using split injection by an autosampler. Injector temperature was 260°C and detector temperature was 270°C. The temperature of the GC was held at 70°C for 5 min, followed by an increase of 2°C/min to 270°C. The final temperature of 270°C was held for 40 min. A control sample was run approximately every fifth sample. Accurate peak measurements (and hence relative concentrations) were obtained from the GC data for highly volatile chemicals detected prior to 54 min. A second 5890 gas chromatograph was linked via a direct interface to a VG70-250SE mass spectrometer (VG Analytical, Manchester, UK) with an interface and re-entrant temperature of 250°C. Electron impact, with an electron energy of 70 eV was used to ionize the analytes. The ion source temperature was 180°C throughout. Repetitive magnetic scanning, over the mass range 450–25, was performed using 0.5 s per mass decayed.
Data analysis
Quantitative data generated by FID were processed and analyzed by a Hewlett Packard ChemStation linked to the gas chromatograph. For all 42 samples the relative retention time of each chemical detected was calculated with respect to the last eluting chemical that was present in all samples (identified as a squalene derivative with a mean elution time ± SEM of 143 ± 0.61 min). In addition, the relative concentration of each chemical detected was computed by dividing the peak area for the chemical (as computed by the ChemStation) by total peak area for all chemicals detected (as computed by the ChemStation). The chemicals present in each pooled scent mark extract were compared by expanding all GC traces on the ChemStation into eight 20 min GC portions. Each GC portion measured 27.75 x 21.5 cm. GC traces were overlaid using the ChemStation and the pattern of peaks examined. Peak parameters assessed included height, shape and spacing in conjunction with relative retention times.
Statistical analysis
Chemicals for which the relative concentration in the scent mark was <0.01% were omitted from the analysis because of unreliable quantification at such low relative amounts. There was little variability in the chemicals detected in the scent marks from the five female marmosets. All female scent marks contained the same, or nearly the same, chemicals. Combined GC and GCMS ascertained that chemicals detected after 54 min sometimes co-eluted, whereas chemicals detected prior to 54 min did not co-elute (see Results). A maximum of 98 chemicals eluted prior to 54 min (defined as highly volatile chemicals). Statistical analysis was only performed for highly volatile chemicals eluting prior to 54 min, excluding six chemicals that appeared to reflect contamination, since the latter were also identified in control material that did not include any scent marks (see Results). Analysis therefore involved 42 scent mark pools and 92 highly volatile chemicals detected in each scent mark.
Stepwise linear discriminant analysis (LDA) was used to test the hypothesis that the relative concentrations of chemicals in the circumgenital scent mark were unique for each individual female. Ten pairwise LDA were performed on data from each possible pairing of females using the StatSoft statistical package (StatSoft, 1991). For each female pair a discriminant function was formed from the information on the relative concentrations of the chemicals in the scent marks. Between four and nine scent mark pools were used from each female to complete each discriminant function (see below). Wilk’s 
was calculated for each discriminant function as a measure of the function’s discriminatory power. Wilk’s statistic was converted to a standard F value and the corresponding P value determined (Rao, 1951). The effectiveness of the discriminant function to correctly classify a scent mark to the correct scent donor was tested using a ‘jack-knife technique’ (Afifi and Clarke, 1996). Briefly, a discriminant function was formed for each pair of females using information from all possible scent marks from the two females minus one. The discriminant function was then used to assign a donor to the remaining scent mark. This process was repeated for all scent marks from the female pair.
|
Results |
|---|
|
TopAbstractIntroductionMaterials and methodsResultsDiscussionReferences |
|---|
Chemical analysis
Scent mark extracts
A total of 162 chemicals were detected by GC in the scent marks of five dominant female marmosets, as illustrated by the individual exemplified in Figure 1. Each of the 162 chemicals had a relative concentration in a scent mark of 
0.01%. Of the 42 pooled samples of scent marks, 86% (36/42) comprised the same 162 chemicals, as illustrated by the two dominant females in Figure 2. The remaining six pooled samples contained a reduced number of these 162 chemicals (range 112–144 chemicals). The latter six pooled samples were not from any particular individual or sub-group of donor females and included female 401W (one pooled sample), female 408W (three pooled samples) and female 272W (two pooled samples). This considerable similarity in chemical composition of scent marks from five marmoset females was confirmed by MS (Table 1).
|
|
|
Control samples
A total of six chemicals were identified in the 20 control samples as probable contaminants. No more than three of the six probable contaminants were found in any single control sample. Probable contaminants were identified as three impurities originating from the extraction solvents (methanol and/or dichloromethane) and three chlorinated chemicals [GC code nos 62, 79 and 95, identified as 2,4-dichloro-3,5-dimethylphenol, 4-chloro-3-methylphenol and phenyl-4-(chloromethyl)phenylether, respectively]. The chlorinated chemicals probably originated from cleansing disinfectants. None of these six chemicals were considered in any quantitative analyses of marmoset scent.
Stepwise linear discriminant analysis
Wilk’s was significant for each discriminant function for all except one of the 10 possible female pair comparisons (Table 2). Using the computed discriminant functions, 91% of scent marks were classified to the correct scent donor using data on the relative concentration of highly volatile chemicals in the scent mark (Table 3).
|
|
|
Discussion |
|---|
|
TopAbstractIntroductionMaterials and methodsResultsDiscussionReferences |
|---|
The study identified 162 chemicals in solvent-extracted scent marks from dominant female common marmosets, of which 112–162 were present in the scent marks of all females. The relative concentrations of volatile chemicals in the scent marks were unique for each female. In this regard individual specific ratios of chemicals in the scent mark might impart an individual odor profile to each female’s scent marks and thus provide a basis for individual discrimination. With human subjects, at least, the ratio in which chemicals are present in a scent mixture can determine the final odor perceived by an individual (Berglund et al., 1973
).
Two previous studies investigating the chemical composition of scent marks from related callitrichid species, male saddle-back tamarins and female cotton-top tamarins, detected considerably smaller numbers of chemicals in scent marks than were found in the present study [16 and 13 chemicals, respectively (Yarger et al., 1977; Belcher et al., 1988)]. The 16 chemicals detected in the scent marks from male saddle-back tamarins were present in all scent marks analyzed in the study. As was found in the present study, the ratio of these 16 chemicals in the scent marks of the saddle-back tamarins was unique for each male (Smith et al., 1985). In contrast to the consistent chemical composition of scent marks from female common marmosets (present study) and male saddle-back tamarins (Smith et al., 1985), scent marks from another closely related callitrichid, the cotton-top tamarin, varied considerably in chemical composition between individual animals (Belcher et al., 1988). Of the 13 chemicals detected in female cotton-top scent marks only three appeared consistently in all samples. Two of the three chemicals (p-methoxybenzaldyhyde and squalene) were also detected in the scent marks of female common marmosets and male saddle-back tamarins. Results from the current study and those of Yarger et al. and Belcher et al. (Yarger et al., 1977; Belcher et al., 1988) suggest that the chemical signaling of individual identity within the callitrichid family is mediated via a wide variety of mechanisms and should not be considered synonymous processes at any level.
Olfactory encoding for individual identity has been observed in a range of mammalian species. Chemical analysis of scent secretions from some mammals has identified quantitative differences in the relative concentrations of chemicals in the odors from individual animals. For example, the anal sac secretion of the Indian mongoose, Herpestes auropunctatus, contains six fatty acids, the relative concentrations of which are unique for each individual animal (Gorman, 1976). The biological activity of fatty acids in the mongoose anal sac secretion was confirmed by the ability of test animals to distinguish between synthetic mixtures containing different ratios of fatty acids (Gorman, 1976). In some species the composition of scent from different individuals varies by both quantitative and qualitative parameters [e.g. European badger, Meles meles, wolves, Canis lupus and mice, Mus musculus (Raymer et al., 1985; Novotny et al., 1990; Buesching and Macdonald, 2000)], whereas in other species qualitative and not quantitative differences are the major distinguishing factors [e.g. shrew, Crocidura russula (Cantoni et al., 1996)]. Although the current study demonstrated clear quantitative differences between scent from individual female marmosets, there might also be qualitative differences between individual scents that were not detected due to the methodological techniques employed. For example, potential qualitative (or quantitative) differences between trace components in the scent mark would not have been detected in the current study, since chemicals were only included in the analyses if their relative concentration in the mark was 0.01%. New World primates demonstrate extremely high levels of olfactory sensitivity (Laska et al., 2000). In the light of the importance of odor to marmoset socio-ecology it is not unlikely that the marmoset olfactory system would have evolved to receive and process trace compounds in scent mixtures.
Quantitative differences between relative concentrations of chemicals in scent secretions have been shown to discriminate attributes of a scent donor other than individual identity. For example, the hormonal status of an individual can be determined by quantitative analysis of the scent secretion [e.g. Iguana iguana (Alberts et al., 1992)] or from analysis of both quantitative and qualitative parameters [e.g. C. lupus and M. musculus (Raymer et al., 1986; Schwende et al., 1986)]. Quantitative differences in scent mark composition have also been shown to distinguish scent from animals of different social status [e.g. white-tailed deer, Odocoileus virginianus (Gassett et al., 1996)]. Phylogenetic analyses of scent secretions have identified quantitative differences in the absence of qualitative differences between scent from different sub-species [e.g. Saguinus fuscicollis (Smith et al., 1985)]. In contrast to the latter example, scent from the anal sac of three different mongoose species (Helogale parvula, Crossarchus obscurus and Suricatta suricatta) were shown to vary both quantitatively and qualitatively (Decker et al., 1992).
The present study identified quantitative differences in the chemical composition of scent marks from individual female common marmosets, but the extent to which marmosets use this quantitative information to distinguish individuality is not known. Future studies will need to focus on behavioral responses to synthetic scent marks that mimic the individual specific ratio of chemicals in natural scent marks to verify the functional relevance of quantitative differences to animal discrimination of individual identity. Epple et al. assessed the discriminatory response of saddle-back tamarins to synthetic scent marks, the chemical composition of which mimicked those identified in the organic solvent extracts of scent marks of two male conspecifics (Epple et al., 1979). Test animals, however, only exhibited discriminatory responses to the natural marks from the two individual males and not to the synthetic versions. The latter results suggest that saddle-back tamarins may use olfactory information in addition to that signaled by chemicals in organic solvent extracts to discriminate individual scent marks (a possibility that cannot be ruled out for common marmosets). Indeed, we have previously shown that common marmosets direct significantly reduced amounts of investigatory behavior toward organic solvent-extracted marks compared with natural marks (Smith, 1994). This latter result suggests that chemicals in addition to those extracted in a solvent extract are necessary for the full communicatory stimulus of the marmoset scent mark, as was the case for the saddle-back tamarin.
The scent mark of the common marmoset is a complex mixture of scents from several sources (Sutcliffe and Poole, 1978). It is therefore not surprising that the solvent-extracted scent marks contained a relatively large number of chemicals and that these chemicals ranged from highly volatile chemicals such as hydrazoic acid to non-volatile proteins (Smith, 1994). Many of the chemicals identified in the scent mark of the female common marmoset feature in the scent secretions of other animals [e.g. aromatic nitrogen-containing chemicals in white-tailed deer, sulfur-containing chemicals in hog-nosed skunk, Conepatus mesoleucus, fatty acids, in lion, Panthera leo, lactone in striped hyaena, Hyaena hyaena (Buglass et al., 1990; Wood et al., 1993; Gassett et al., 1996; Andersen and Vulpius, 1999)] and have proven pheromonal effects [e.g. 2,5-dimethylpyrazine (Novotny et al., 1990)]. Certain biochemical properties might render some compounds more effective chemical signals than others and thus favor their evolution as olfactory signals. For example, chemicals with high odor potency [e.g. sulfur-containing chemicals (Novotny et al., 1974)] and low odor thresholds [e.g. pyrazines (Barlin, 1982)] might be highly effective odor signals since only a small amount of compound is required to cause an effect in recipient animals. The biochemical pathway by which a compound is formed might also influence its evolution as a chemical signal. For example, aromatic nitrogen-containing compounds can be readily formed from the microbial degradation of proteins. In the light of the constant source of urinary proteins in the marmoset ano-genital area, together with its rich microbial flora (Nordstrom et al., 1989), it is not surprising that a variety of aromatic nitrogen-containing compounds were identified in the marmoset scent mark.
In considering the functional significance of individual-specific odors of dominant female common marmosets it has been shown that individual-specific odors from dominant females regulate hypothalamic–pituitary–gonadal function in subordinate females (Barrett et al., 1990). In captive social groups of adult common marmosets subordinate females do not usually ovulate (Abbott, 1984). Anovulatory subordinate females removed from their social group and housed singly commence ovulatory cycles within 10 days of single cage housing unless they are maintained in olfactory contact with their dominant female. In the latter case, time to onset of the first ovulation is extended to 30 days (Barrett et al., 1990, 1993). The period of anovulation following removal from the social group is not extended beyond that of control animals (i.e. 10 days) if the isolated females were maintained in scent contact with an unfamiliar dominant female (Smith and Abbott, 1995). As scent from a familiar, but not an unfamiliar, dominant female maintains anovulation in subordinate females, reproductive suppression in female marmosets cannot be mediated via a primer pheromonal effect. Instead, Abbott et al. suggest that classical conditioning might maintain anovulation in subordinate females (Abbott et al., 1997). They also propose that early harassment by the dominant female during group formation (unconditioned stimulus) provokes anovulation (unconditioned response) in subordinate females. Subordinate females subsequently learn to associate individual characteristics of the dominant female (such as her unique odor profile) with harassment. Eventually the individual-specific characteristics of the dominant female become the conditioned stimuli eliciting a conditioned response of anovulation in subordinate females. The importance of odor for initiating reproductive suppression in marmosets is confirmed by the observation that while anosmic females exhibit behavioral subordination during group formation they continue to ovulate (Abbott et al., 1993). Results from the current study are compatible with a classical conditioning model (Abbott et al., 1997), since we have shown that scent marks from individual dominant female marmosets have unique chemical compositions and have the potential to impart individual-specific odor to the scent mark. Implicit in the classical conditioning model is the assumption that subordinate females have the neural substrates from which to form a relatively long-lasting memory (i.e. up to 30 days) of complex odor profiles. Common marmosets maintain memory traces for visual stimuli for up to 1 year, suggesting that they might also possess the neural physiology to maintain olfactory memories for extended periods of time (L. Scott, personal communication). Mammalian olfactory learning can involve both the accessory olfactory bulb [mice (Lloyd-Thomas and Keverne, 1982)] and the main olfactory bulb [ewes (Levy et al., 1995)]. Marmosets possess an accessory olfactory system together with a functional vomeronsasal organ, in addition to the main olfactory system (Harrison, 1987; Taniguchi et al., 1992). Since both the accessory and main olfactory epithelium have neural connections to the hypothalamus, the neural substrates for olfactory learning and subsequent neuroendocrine responses could involve either site (Scalia and Winans, 1976). Since highly volatile chemicals distinguished the scent from individual dominant females (current study), olfactory learning of the dominant female’s scent profile might primarily involve the main olfactory bulb: volatile chemicals tend to be received by the main olfactory system (Meredith, 1991). Alternatively, the volatile chemicals distinguishing scent from individual dominant females might be attached to non-volatile carrier proteins in the scent mark (Singer, 1991), implicating involvement of the accessory olfactory bulb in olfactory memory formation and the neuroendocrine events leading to anovulation (non-volatile cues are received primarily via the vomeronasal organ). A further understanding of the olfactory system and neural pathways mediating olfactory learning in marmosets might help to refine our understanding of the chemical components in common marmoset scent marks relevant to distinguishing individual identity.
|
Acknowledgments |
|---|
The authors thank Mike Llovett, Judy Bidgood and the Animal Care staff at the Institute of Zoology, Zoological Society of London, for their expert care of the marmosets. All scent mark collection equipment and scent mark presentation frames were constructed by George Ray, to whom we are extremely grateful. Support and encouragement were provided by Dr H. D. M. Moore and the Institute of Zoology, Zoological Society of London, UK. Comments on earlier drafts of the manuscript were made by Dr Jeffrey A. French and two anonymous reviewers. Professor Boyd and Professor Mann, School of Chemistry, Queen’s University of Belfast, provided valuable advice on chemical nomenclature. The project was funded by a grant from Dalgety plc, UK (to D.H.A. and T.E.S.). This is publication number 37-005 of the Wisconsin Regional Primate Research Center.
|
References |
|---|
|
TopAbstractIntroductionMaterials and methodsResultsDiscussionReferences |
|---|
Abbott, D.H. (1984) Behavioral and physiological suppression of fertility in subordinate marmoset monkeys. Am. J. Primatol., 6, 169–186.
Abbott, D.H., Hodges, J.K. and George, L.M. (1988) Social status controls LH secretion and ovulation in female marmoset monkeys (Callithrix jacchus). J. Endocrinol., 117, 329–339.
Abbott, D.H., Faulkes, C.G., Barrett, J., Smith, T.E. and Cheeseman, D.J. (1993) Social control of female reproduction in marmoset monkeys and naked mole-rats. In Lehnert, H., Murison, R., Weiner, H., Hellhammer, D. and Beyer, J. (eds), Endocrine and Nutritional Control of Basic Biological Functions. Hogrefe and Huber, Seattle, pp. 475–489.
Abbott, D.H., Saltzman, W., Schultz-Darken, N.J. and Smith, T.E. (1997) Specific neuroendocrine mechanisms not involving generalized stress mediate social regulation of female reproduction in cooperatively breeding marmosets monkeys. Ann. N. Y. Acad. Sci., 807, 219–238.[Web of Science][Medline]
Afifi, A.A. and Clark, V. (1996) Computer-Aided Multivariate Analysis, Texts in Statistical Science Series. Chapman & Hall: London.
Alberts, A.C., Sharp, T.R., Werner, D.I. and Weldon, P.J. (1992) Seasonal variation of lipids in femoral gland secretions of male green iguanas (Iguana iguana). J. Chem. Ecol., 5, 703–712.
Andersen, K.F. and Vulpius, T. (1999) Urinary volatile constituents of the lion, Panthera leo. Chem. Senses, 24, 179–189.
Barlin, G.B. (1982) The Pyrazines. The Chemistry of Heterocyclic Compounds. John Wiley & Sons, New York.
Barrett, J., Abbott, D.H. and George, L.M. (1990) Extension of reproductive suppression by pheromonal cues in subordinate female marmoset monkeys, Callithrix jacchus. J. Reprod. Fertil., 90, 411–418.
Barrett, J., Abbott, D.H. and George, L.M. (1993) Sensory cues and the suppression of reproduction in subordinate female marmoset monkeys, Callithrix jacchus. J. Reprod. Fertil., 97, 301–310.
Belcher, A., Epple, G., Kuderling, I. and Smith, A.B. (1988) Volatile components of scent material from Cotton-top Tamarin (Saguinus o. oedipus). J. Chem. Ecol., 14, 1367–1384.
Berglund, B., Berglund, U., Lindvall, T. and Svensson, L.T. (1973) A quantitative principle of perceived intensity summation in odor mixtures. J. Exp. Psychol., 100, 29–38.[Web of Science][Medline]
Buesching, C.D. and Macdonald, D.W. (2000) Faeces and subcaudal gland secretions—the smell of the European badger (Meles meles). Abstract book, Chemical Signals in Vertebrates IX, p. 26. Jagiellonian University, Kraków, Poland.
Buglass, A.J., Darling, F.M.C. and Waterhouse, J.S. (1990) Analysis of the anal sac secretion of the hyaenidae. In Macdonald, D.W., Muller-Schwarze, D. and Natynczuk, S.E. (eds), Chemical Signals in Vertebrates 5. Plenum Press, New York, pp. 415–429.
Cantoni, D., Favre, L., Tencalla, F., Croset, P., Morgenthaler, F., Camarda, G., Ruchet, C., Rivier, L. and Vogel, P. (1996) Intra- and interindividual variation in flank gland secretions of free-ranging shrews Crocidura russula. J. Chem. Ecol., 9, 1669–1688.
Coimbra-Filho, A.F. and Mittermeier, R.A. (1976) Exudate-eating and tree-gouging in marmosets. Nature, 262, 630.
Coimbra-Filho, A.F. and Mittermeier, R.A. (1978) Tree-gouging, exudate-eating and the ‘short-tusked’ condition in Callithrix and Cebuella. In Kleiman, D. (ed.), The Biology and Conservation of the Callitrichidae. Smithsonian Institute Press, Washington, DC, pp. 105–115.
Coopersmith, C.B. and Banks, E.M. (1983) Effects of olfactory cues on sexual behavior in the brown lemming, Lemmus trimucronatus. J. Comp. Psychol., 97, 120–126.[Web of Science][Medline]
Decker, D.M., Ringelberg, D. and White, D.C. (1992) Lipid components in the anal sacs of three mongoose species (Helogale parvula, Crossarchus obscurus, Suricatta suricatta). J. Chem. Ecol., 9, 1511–1524.
Dugmore, S.J. and Evans, C.S. (1990) Discrimination of conspecific chemosignals by female ringtailed lemurs, Lemur catta L. In Macdonald, D.W., Muller-Schwarze, D. and Natynczuk, S.E. (eds), Chemical Signals in Vertebrates 5. Plenum Press, New York, pp. 360–366.
Epple, G. (1970) Quantitative studies on scent marking in the marmoset (Callithrix jacchus jacchus). Folia Primatol., 13, 48–62.
Epple, G., Golob, N.F. and Smith, A.B. (1979) Odor communication in the tamarin Saguinus fuscicollis (Callitrichidae). Behavioural and chemical studies. In Ritter, F.J. (ed.), Chemical Ecology: Odor Communication in Animals. Elsevier North-Holland Biomedical Press, Amsterdam, The Netherlands, pp. 117–130.
Epple, G., Belcher, A.M., Kuderling, I., Zeller, U., Scolnock, L., Greenfield, K.L. and Smith, A.B. (1993) Making sense out of scents: species differences in scent glands, scent-marking behaviour, and scent mark composition in the Callitrichidae. In Rylands, A.B. (ed.), Marmosets and Tamarins: Systematics, Behaviour and Ecology. Oxford University Press, Oxford, UK, pp. 123–151.
Gassett, J.W., Wiesler, D.P., Baker, A.G., Osborn, D.A., Miller, K.V., Marchinton, R.L. and Novotny, M. (1996) Volatile compounds from interdigital gland of male white-tailed deer (Odocoileus virginianus). J. Chem. Ecol., 22, 1689–1696.
Gorman, M.L. (1976) A mechanism for individual recognition by odour in Herpestes auropunctatus (Carnivora: Viverridae). Anim. Behav., 2, 141–145.
Gosling, L.M. and McKay, H.V. (1990) Competitor assessment by scent matching: an experimental test. Behav. Ecol. Sociobiol., 26, 415–420.
Halpin, Z.T. (1986) Individual odors among mammals: origins and functions. Adv. Study Anim. Behav., 16, 39–70.
Harrison, D. (1987) Preliminary thoughts on the incidence, structure and function of the mammalain vomeronasal organ. Acta Otolaryngol. (Stock.), 103, 489–495.[Medline]
Harlow, C.R., Hearn, J.P. and Hodges, J.K. (1983) Ovulation in the marmoset monkey: endocrinology, prediction and detection. J. Endocrinol., 103, 17–24.
Holmes, D.J. (1992) Odors as cues for orientation to mothers by weanling Virginia opossums. J. Chem. Ecol., 18, 2251–2259.
Johnston, R.E., Derzie, A., Chiang, G., Jernigan, P. and Lee, H. (1993) Individual scent signatures in golden hamsters: evidence for specialization of function. Anim. Behav., 45, 1061–1070.
Laska, M. and Hudson, R. (1995) Ability of female squirrel monkeys (Saimiri sciureus) to discriminate between conspecific urine odours. Ethology, 99, 39–52.
Laska, M., Seibt, A. and Weber, A. (2000) ‘Microsmatic’ primate revisited: olfactory sensitivity in the squirrel monkey. Chem. Senses, 25, 47–53.
Lazaro-Perea, C., Snowdon, C.T. and de Fatima Arruda, M. (1999) Scent-marking behaviour in wild groups of common marmosets (Callithrix jacchus). Behav. Ecol. Sociobiol., 46, 313–324.
Levy, F., Locatelli, A., Piketty, V., Tillet, Y. and Poindron, P. (1995) Involvement of the main but not the accessory olfactory system in maternal behaviour of primiparous and multiparous ewes. Physiol. Behav., 57, 97–104.[Medline]
Lloyd-Thomas, A. and Keverne, E.B. (1982) Role of the brain and accessory olfactory system in the block to pregnancy in mice. Neuroscience, 7, 907–913.[Web of Science][Medline]
Meredith, M. (1991) Sensory processing in the main and accessory olfactory systems: comparisons and contrasts. J. Steroid Biochem. Mol. Biol., 39, 601–615.[Web of Science][Medline]
Mykytowycz, R. (1973) Reproduction of mammals in relation to environmental odours. J. Reprod. Fertil., 19 (suppl.), 433–446.
Newman, K.S. and Tang Halpin, Z.T. (1988) Individual odours and mate recognition in the prairie vole, Microtus ochrogaster. Anim. Behav., 36, 1779–1787.
Nordstrom, K.M., Belcher, A.M., Epple, G., Greenfield, K.L., Leyden, J.J. and Smith, A.B. (1989) Skin surface microflora of the saddle-back tamarin monkey, Saguinus fuscicollis. J. Chem. Ecol., 15, 629–639.
Novotny, M., Lee, M.L. and Bartle, K.D. (1974) Some analytical aspects of the chromatographic headspace concentration method using a porous polymer. Chromatographia, 7, 333–338.
Novotny, N., Jemiolo, B. and Harvey, S. (1990) Chemistry of rodent pheromones. Molecular insights into chemical signalling in mammals. In Macdonald, D.W., Muller-Schwarze, D. and Natynczuk, S.E. (eds), Chemical Signals in Vertebrates 5. Plenum Press, New York, pp. 1–22.
Rao, C.R. (1951) An asymptotic expansion of the distribution of Wilk’s criterion. Bull. Int. Statist. Inst., 33, 177–181.
Raymer, J., Wiesler, D., Novotny, M., Asa, C., Seal, U.S. and Mech, L.D. (1985) Chemical investigations of wolf (Canis lupus) anal-sac secretion in relation to breeding season. J. Chem. Ecol., 5, 593–608.
Raymer, J., Wiesler, D., Novotny, M., Asa, C., Seal, U.S. and Mech, L.D. (1986) Chemical scent constituents in urine of wolf (Canis lupus) and their dependence on reproductive hormones. J. Chem. Ecol., 12, 297–314.
Rylands, A.B. (1993) Marmosets and Tamarins: Systematics, Ecology and Behaviour. Oxford University Press, Oxford, UK.
Scalia, F. and Winans, S.S. (1976) New perspectives on the morphology of the olfactory system: olfactory and vomeronasal pathways in mammals. In Doty, R.L. (ed.), Mammalian Olfaction, Reproductive Processes and Behavior. Academic Press, New York, pp. 7–28.
Schwende, F.J., Wiesler, D., Jorfenson, J.W., Carmack, M. and Novotny, M. (1986) Urinary volatile constituents of the house mouse, Mus musculus, and their endocrine dependency. J. Chem. Ecol., 12, 277–296.[Web of Science]
Singer, A.G. (1991) A chemistry of mammalian pheromones. J. Steroid. Biochem. Mol. Biol., 39, 627–633.[Web of Science][Medline]
Smith, A.B., Belcher, A.M., Epple,E., Jurs, P.C. and Lavine, B. (1985) Computerized pattern recognition: a new technique for the analysis of chemical communication. Science, 228, 175–176.
Smith, T.E. (1994) The role of odour in the suppression of reproduction in female naked mole-rats (Heterocephalus glaber) and common marmosets (Callithrix jacchus) and the social organization of these two species, unpublished doctoral dissertation, University of London.
Smith, T.E. and Abbott, D.H. (1995) Olfactory cues from unfamiliar dominant female common marmosets fail to maintain ovarian suppression in singly housed subordinates. Am. J. Primatol. Abstr. Ser., 36, 131.
Smith, T.E. and Abbott, D.H. (1998) Behavioral discrimination between circumgenital odor from peri-ovulatory dominant and anovulatory female common marmosets (Callithrix jacchus). Am. J. Primatol., 46, 265–284.[Web of Science][Medline]
Smith, T.E., Abbott, D.H., Tomlinson, A.J. and Mlotkiewicz, J.A. (1997) Differential display of investigative behavior permits discrimination of scent signatures from familiar and unfamiliar socially dominant female marmoset monkeys (Callithrix jacchus). J. Chem. Ecol., 23, 2523–2546.
Sutcliffe, A.G. and Poole, T.B. (1978) Scent marking and associated behaviour in captive marmosets (Callithrix jacchus jacchus) with a description of the histology of the scent glands. J. Zool., 185, 41–56.
Tang-Martinez, Z., Mueller, L.L. and Taylor, G.T. (1993) Individual odours and mating success in the golden hamster, Mesocricetus auratus. Anim. Behav., 45, 1141–1151.
Taniguchi, K., Matsusaki, Y., Ogawa, K. and Saito, T.R. (1992) Fine structure of the vomeronasal organ in the common marmoset (Callithrix jacchus). Folia Primatol., 59, 169–176.
Wood, W.F., Fisher, C.O. and Graham, G.A. (1993) Volatile components in defensive spray of the hog-nosed skunk, Conepatus mesoleucus. J. Chem. Ecol., 19, 837–841.
Yarger, R.G., Smith, A.B., Preti, G. and Epple, G. (1977) The major volatile constituents of the scent mark of a South American primate, Saguinus fuscicollis. Callitrichidae. J. Chem. Ecol., 3, 45–56.[Web of Science]
Accepted November 29, 2000
CiteULike 
Connotea 
Del.icio.us What's this?
This article has been cited by other articles:
|
|
 |
|
  E. Palagi and L. Dapporto Females do it better. Individual recognition experiments reveal sexual dimorphism in Lemur catta (Linnaeus 1758) olfactory motivation and territorial defence J. Exp. Biol., August 1, 2007; 210(15): 2700 - 2705. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
K. Matsumura, S. Matsunaga, and N. Fusetani Phosphatidylcholine profile-mediated group recognition in catfish J. Exp. Biol., June 1, 2007; 210(11): 1992 - 1999. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 E. S. Scordato, G. Dubay, and C. M. Drea Chemical Composition of Scent Marks in the Ringtailed Lemur (Lemur catta): Glandular Differences, Seasonal Variation, and Individual Signatures Chem Senses, June 1, 2007; 32(5): 493 - 504. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
E. Palagi and L. Dapporto Beyond Odor Discrimination: Demonstrating Individual Recognition by Scent in Lemur Catta Chem Senses, June 1, 2006; 31(5): 437 - 443. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
J.-X. Zhang, J. Ni, X.-J. Ren, L. Sun, Z.-B. Zhang, and Z.-W. Wang Possible Coding for Recognition of Sexes, Individuals and Species in Anal Gland Volatiles of Mustela eversmanni and M. sibirica Chem Senses, June 1, 2003; 28(5): 381 - 388. [Abstract] [Full Text] [PDF]
|
|
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||