Lixing Sun

Anal gland secretion codes for family membership in the beaver

Abstract We investigated how information about family membership is coded by the individually specific anal gland secretion (AGS) in the beaver, Castor canadensis. Because beavers live in strict family units and relatives share more features in the AGS profile than non-relatives, family members share more AGS features than non-family members. Therefore, family recognition seems to be a natural consequence of the more specific kin recognition. Multivariate statistical analyses revealed two possibilities in coding for family membership using the multi-component AGS: either two (female) to three (male) AGS compounds or many compounds were used, but we were not able to determine which possibility is more likely. Compounds were not equally important in coding family membership information, and the interactions among compounds were complex. We attempted to reconstruct a lineage tree for the relationship among different families using two–three or many compounds. We found there was no significant difference for trees constructed by using few or many compounds in either males or females. However, the trees derived from male compounds and female compounds lacked good congruence.

Use of anal gland secretion to distinguish the two beaver species Castor canadensis and C. fiber

Introduced North American beavers Castor canadensis pose a potential threat to the continuing recovery of Eurasian beaver C. fiber populations in several European countries. For management purposes, it is necessary to be able to identify and distinguish the two species. This, however, is difficult because the two species are morphologically, ecologically and behaviourally similar. To find a method for species identification, we examined the possibility of using anal gland secretion (AGS) collected from the two beaver species. We asked 20 inexperienced volunteers to inspect the colour and viscosity of the AGS. When we provided the volunteers with the sex of each beaver and descriptions of the colour and viscosity of AGS from males and females of the two species, all volunteers could 100% correctly identify the two species. We therefore conclude that the colour and viscosity of the AGS can be used for a quick and easy identification of the two beaver species.

Effects of weasel odor on behavior and physiology of two hamster species.

This study examined the behavioral and physiological effects of long-term exposure to overdose of aversive odor (predator odor) in two species of hamsters. About 0.05 mg of anal gland secretions of Siberian weasels (Mustela sibirica) was smeared at the oronasal groove of wild male ratlike hamsters (Cricetulus triton) (natural prey) and laboratory golden hamsters (Mesocricetus auratus) once every day for 4 weeks. After 28 days, the experimental groups of both hamster species displayed higher cortisol level, larger adrenal gland (in ratlike hamsters only), smaller thymus and flank gland, and lower aggression level than the conspecific control group (presented with water). Thus, the long-term presence of overdose of the anal gland secretion of the Siberian weasel could lower the aggression and social rank and suppress the immunity in the hamsters. The reproductive conditions of these prey species, however, seemed not to be affected. In addition, the similarities in the behavioral and physiological responses to the predator odor between the two species of hamsters showed that the responses to predator odor might be innate.

Dual Role of Preputial Gland Secretion and its Major Components in Sex Recognition of Mice

This study was aimed at validating the sexual attractiveness of hexadecanol and hexadecyl acetate, two putative pheromone compounds, from preputial gland secretion of mice. These two compounds have been reported to be among the major components of preputial gland secretion in both sexes but higher in quantity in males than females. In this study, we show that castration suppressed the production of the two compounds, further suggesting their association with maleness. Adding preputial gland secretion and the synthetic analogs of the two compounds to castrated male urine at their physiological levels in intact males increased the attractiveness of castrated male urine to female mice, showing that the two compounds were indeed male pheromones. Furthermore, their sexual attractiveness disappeared upon removing the vomeronasal organs (VNOs) from female recipients. Replenishing castrated male urine with preputial gland secretion and the two compounds at their physiological levels in females increased the attractiveness of castrated male urine to males. Such a reversal of sexual attractiveness for hexadecanol and hexadecyl acetate suggests that they had opposing dual effects in sexual attractiveness in a dosage-dependent manner.

Volatile Compounds in Anal Gland of Siberian Weasels (Mustela sibirica) and Steppe Polecats (M. eversmanni)

The volatile constituents in anal gland secretions of two sympatric Mustela species, the Siberian weasel (M. sibirica) and steppe polecat (M. eversmanni), were studied by the headspace technique, followed by gas chromatography–mass spectrometry (GC-MS) analysis. Nine sulfur-containing compounds were identified. They were 2,2-dimethylthietane, (Z)- or (E)-2,4-dimethylthietane, (E)-2,3-dimethylthietane, 2-ethylthietane, (E)-2-ethyl-3-methylthietane, (Z)-2-ethyl-3-methylthietane, 2-propylthietane, 3,3-dimethyl-1,2-dithiacyclopentane, and (Z)-3,4-dimethyl-2,2-dithiacyclopentane. Among them, (E)-2-ethyl-3- methylthietanes, (Z)-2-ethyl-3-methylthietanes, and (Z)-3,4-dimethyl-1,2-dithiacyclopentane were present in the polecat but not in the weasel. The predominant compound was 2,2-dimethylthietane in the weasel and (E)- or (Z)-2,4-dimethylthietane in the polecat. These differences were consistent between the two species, regardless of sex and age and, therefore, could possibly be used for species recognition. In the weasel, 2-ethylthietane was found only in the female, and the relative abundance of several compounds was significantly different between males and females. In the polecat, although no sex-specific volatile compounds were found, males and females differed in the relative abundance of several of the compounds. In both species, the relative abundance of some compounds varied with age. We conclude that these volatile compounds can be used to communicate information about species, sex, and age.

Using anal gland secretion to determine sex in beaver

Controlling beaver (Castor canadensis) populations is a problematic issue for wildlife managers in North America. Management of beaver can be facilitated by determining sex ratio of a population, but this requires ready identification of gender for live and harvested beaver. We developed a technique using color and viscosity of anal gland secretion (AGS) to identify gender of beaver. Inexperienced volunteers inspected AGS from beaver in 3 regions of New York. Using AGS collected and stored in glass vials, 4 volunteers correctly identified sex of 24 beaver (16 M, 8 F) livetrapped during spring 1992; 2 additional pairs of volunteers correctly discriminated 45 beaver (21 M, 24 F) livetrapped in spring 1993 and 1994. Using fresh AGS viewed in the field, 1 volunteer correctly discerned 25 beaver (15 M, 10 F) caught in October 1993; and 2 volunteers distinguished sex of 5 beaver (3 M, 2 F) captured in November 1992 without error. Male AGS was Kraft brown (P55, Marker color system) to sepia (P56) and viscous (490-507 centipoise [cP] at 25.8 C and 60 rpm, Brookfield DV-11 + viscometer), while female secretion was pale to medium olive (P34, P39) or warm gray (P191), less viscous (4-28.7 cP, 23-25.4 C, 50 or 100 rpm) and flowed more (P < 0.001) than male AGS. Secretion color and viscosity were discriminating means of distinguishing the sexes in the field.

Grooming Reciprocity in Female Tibetan Macaques Macaca Thibetana

Grooming among nonhuman primates is widespread and may represent an important service commodity that is exchanged within a biological marketplace. In this study, using focal animal sampling methods, we recorded grooming relationships among 12 adult females in a free‐ranging group of Tibetan macaques (Macaca thibetana) at Huangshan, China, to determine the influence of rank and kinship on grooming relationships, and whether females act as reciprocal traders (exchange grooming received for grooming given) or interchange traders (interchange grooming for social tolerance or other commodities). The results showed that: (1) grooming given was positively correlated with grooming received; (2) kinship did not exert a significant influence on grooming reciprocity; and (3) grooming reciprocity occurred principally between individuals of adjacent rank; however, when females of different rank groomed, females tended to groom up the hierarchy (lower ranking individuals groomed higher ranking individuals more than vice versa). Our results support the contention that both grooming reciprocity and the interchange of grooming for tolerance represent important social tactics used by female Tibetan macaques. Am. J. Primatol. 74:569–579, 2012.

Potential Chemosignals in the Anogenital Gland Secretion of Giant Pandas, Ailuropoda melanoleuca, Associated with Sex and Individual Identity

With a combination of dichloromethane extraction and analysis by gas chromatography–mass spectrometry (GC-MS), we found 39 compounds (corresponding to 38 GC peaks) in the anogenital gland secretion (AGS) of captive adult giant pandas, Ailuropoda melanoleuca, during the non-mating season. In addition to indole, squalene, and some of the straight-chain fatty acids that had been characterized previously from the AGS of giant pandas, we identified several new compounds such as decenal, two isomers of decadienal, phenylacetic acid, 5-methylhydantoin, hydroquinone, phenylpropanoic acid, and erucic acid. Quantitative comparison of the relative abundances of the 20 main GC peaks revealed that 5-methylhydantoin, indole, and erucic acid are putative female pheromones, whereas squalene and hydroquinone are putative male pheromones. In addition to the presence of a few individual-specific compounds, the relative abundances of most of the 21 constituents varied more among individuals than within individuals. This suggests that individual identity might be coded in both digital and analog form. The chemical composition of different AGS samples from the same pandas consistently displayed a minimum cluster distance, much smaller than that between samples from different individuals in a hierarchical linkage cluster (average linkage) dendrogram. Our results indicate that the AGS might contain an “odor fingerprint.” Although putative sex pheromones such as squalene and erucic acid should be assessed further by bioassay, our study suggests that synthetic chemosignals might be useful in modulating the behavior and physiology of giant pandas.

Mice Respond Differently to Urine and Its Major Volatile Constituents from Male and Female Ferrets

Our previous chemical investigation showed that the concentrations of urinary volatiles from males were much higher than those from females in the ferret (Mustela furo). The current study was designed to examine the behavioral significance and ecological relevance of this difference for one of the main prey of the ferret, the house mouse (Mus musculus). Our data showed that male mice displayed no difference in their response to raw male and female ferret urine. However, they showed significantly less response to female mouse urine mixed with ferret urine than to pure female mouse urine, and to female mouse urine mixed with male ferret urine than to female mouse urine mixed with female ferret urine. Furthermore, high levels of the three major volatiles (quinoline, 2,5-dimethylpyrazine, and 4-hepatanone) in male ferret urine were as effective as raw male ferret urine was in inhibiting the response of male mice. We discuss the ecological and behavioral significance of these findings in terms of chemical mimicry and cognitive feature extraction of predator odors in mice.

Foxn1 Gene Knockout Suppresses Sexual Attractiveness and Pheromonal Components of Male Urine in Inbred Mice

The immunocompetence handicap hypothesis (ICHH) posits that females prefer signals emitted by immunocompetent males over immunocompromised males and that these signals are honest. However, mechanisms of mate choice under an ICHH model may be impacted by levels of genetic variation (inbred animals vs. outbred animals). Here, we conducted 2-choice female preference experiments and chemical analyses of male urine in inbred BALB/c and outbred CD-1 mice, both of which have immunocompromised nude (nu) strains resulting from a Foxn1 gene knockout. We found that inbred BALB/c females but not outbred CD-1 females preferred the urine of healthy males over that of immunocompromised males despite measured differences in the qualities of their urine. There was a clear increase in female-attracting pheromones (such as farnesenes) in the preputial glands and urine metabolites in healthy BALB/c males but no such difference between CD-1 and CD-1 nu males. Therefore, CD-1 male urine failed to provide an honest mate-choice cue for females. Our results suggest that deleterious traits associated with male odor in mice might be jointly affected by the level of inbreeding and immunodeficiency caused by a single-gene knockout.