Status dominance

Abstract For most mammals, the ability to detect odours and discriminate between them is necessary for survival. Information regarding the availability of food, the presence of predators and the sex, age and dominance status of conspecifics is odour mediated. Probably because of this extraordinary reliance upon odour cues, mice and rats have developed the ability to learn and remember information associated with olfactory cues as effectively as primates recall visually related cues. As a result, these rodents have become the model of choice to study the neural and cognitive processes involved in olfactory discrimination. In this paper, we describe some of the more ethologically based tasks used in assessing olfactory discrimination and the advantages and disadvantages of the different methodologies employed. 

In mammals, olfactory cues play an important role in sexual selection, both during matechoice and male contests (Andersson 1994) and as olfactory cues are almost always multi-component, they provide a multitude of possibilities to encode information (Albone 1984). Chemical signals may provide information about health (Penn and Potts 1998 Kavaliers, Colwell, Braun and Choleris 2003 Zala, Potts and Penn 2004), dominance status (Gosling and Roberts 2001), sex and group membership (Hofer, East, Sammang and Dehnhard 2001 Safi and Kerth 2003) respectively population affiliation (Hayes, Richardson, Claus and Wyllie 2002). 

Metabolites in urine or feces provide the energetically least expensive, and evolutionarily probably the original, chemical signals in vertebrates. Much of history of evolution has concerned the development by living things of responses to metabolites, sometimes their own and sometimes produced by others. Those organisms which developed satisfactory responses succeeded, and those which did not, failed. (Lucas, 1944). Interested parties, such as members of the opposite sex, can then spy and read pertinent information about sexual and dominance status, health and body condition, quality of diet, and more. For instance, female goldfish release sex pheromones in their urine that... 

Dominance status information, coded in whole-body odor, can travel between animals in an air stream. When exposed to the odor of a familiar, dominant male, the sugar glider, P. breviceps, increases cardiac and respiration rates within 10 minutes, and levels of glucose and catecholamine in the plasma rise after 30 minutes (Stoddart and Bradley, 1991). 

In other rodents, subordinate males also smell scent marks quite often and so keep informed on the presence, status and activities of higher-ranking group members. For instance, dominant males of the hispid cotton rat, Sigmodon hispidus, urine mark more than subordinates. The social status of the male urine donor affects the response of other males to the odor. The response of a reproductive female to feces of either sex depends on her dominance status (Gregory and Cameron, 1989). 

The dominance status of an individual can be predicted by its scent-marking rate before social interactions take place Woodchucks Marmota monax) scent mark with their oral glands. When presented with isolated secretion of the oral gland of other woodchucks, future subordinates marked the scent of future dominant animals more often than vice versa (Hebert and Barette, 1989). 

The concentrations of 16 constituents of male mouse urine vary with the male s dominance status. Dihydrofurans, ketones, and acetates decreased in subordinates. Two sesquiterpene compounds, a- and /3-farnesene, are elevated in dominants urine 1 week after establishing dominance. The bladder or voided urine of dominants contains more 2-5ec-butyl-4,5-dihydrothiazole. Four compounds depend on hormones a- and /5-farnesene, dehydro-exo-brevicomin, and 2-5cc -butyl-4,5-dihydrothiazole. The latter two are absent in urine of immature or castrated males, and testosterone treatment restores their presence. In addition, a-and /3-farnesene do not occur in urine of immature males and are merely reduced in urine of castrates. They are not found in bladder urine and originate in the preputial glands (Harvey etal., 1989). While subordinate male mice have reduced levels of farnesenes, levels of their major urinary proteins remain high (Malone etal, 2001). 

Hydrocarbon profiles indicate fertility and dominance status in ant, bee, and wasp colonies... 

The social organization of insect colonies indicates the importance of information that is usually not needed in solitary insects. Information about the presence and fertility of a queen strongly affects worker behavior and colony organization. Reproductive competition in colonies requires the correct assessment of each others rank. All of this information about fertility status and/or dominance status can be encoded in the cuticular hydrocarbon profile of members of ant, wasp, and bee colonies. Understanding variations in these hydrocarbon profiles, their composition, and relation to fertility is key to the further understanding of the major property of eusocial insects, reproductive division of labor. 

Fertility and dominance status in colonies Effects on worker reproduction... 

We will test responses of male and female mice to urine from males and females. Each group will first run a male, then replace the tubes with clean ones, and run a female. To make the test more specific, we can first determine the dominance status of the odor donor by staging encounters, and then specifically observe responses to dominant or subordinate individuals. 

Due to their strong reproductive investment, female crayfish are expected to be highly selective in the choice of the mate. Female quality assessment could include size and dominance status of males, which both affect the resource holding potential... 

Yeh SR, Musolf BE, Edwards DH (1997) Neuronal adaptations to changes in the social dominance status of crayfish. J Neurosci 17 697-708... 

Zulandt Schneider RA, Schneider RWS, Moore PA (1999) Recognition of dominance status by chemoreception in the red swamp crayfish, Procambarus clarkii. J Chem Ecol 25 781-794... 

Surprisingly, dominance status signals have been never investigated in anomur-ans, as, on the contrary, abundantly done in crayfish (Breithaupt, Chap. 13). 

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