The Market Effect in the Wood Mouse,Apodemus sylvaticus:Selling Information on Reproductive Status

Abstract

Grooming in the wood mouse is a means by which males obtain information about the reproductive state of females, as grooming creates a situation which allows the male to smell the groomed female’s anogenital area to ascertain her phase of oestrus. Although grooming is reciprocal in this species, it is asymmetrical in that males groom females more often than vice versa. This grooming asymmetry was studied using Markov chain analysis for grooming sequences in two captive wood mouse colonies, and transition rates were used to represent motivation in both sexes. Grooming sessions were often initiated by a male’s attempt to sniff an immobile female’s anogenital region, while the female would immediately react by avoiding or biting the male. In order to entice the female to remain, the male would begin grooming the female’s head and shoulder area, surreptitiously and consistently grooming downwards towards the female’s anogenital region, until she would again terminate such contact either by avoiding or biting the male. While, therefore, the male’s tendency to sniff the female’s anogenital region was stronger than his tendency to groom her, the female’s tendency to terminate the male’s naso‐anal contact was much stronger than her tendency to terminate his grooming bouts. If the male did not initiate grooming after the female terminated naso‐anal contact, she avoided further contacts and escaped. In mice, as in most mating systems, the demand for matings by males is far larger than the number of matings females offer. The mating market, therefore, is highly skewed, which gives females the opportunity to demand ‘commodities’ in return for allowing males to mate. This system allows females to ‘bargain’ with males to obtain grooming in return for anogenital contact. Females assess the length of time they receive grooming and will only allow males to attain anogenital contact after a certain threshold value has been passed. If anogenital contact provides the male with information about the female’s reproductive state and/or with sexual stimulation, then this process represents the first quantified example in short‐lived mammals of females ‘selling sex’ in terms of the market effect. This paper therefore provides a new view of the regulation of grooming: grooming is not simply reciprocal with both participants concerned that the other does not ‘cheat’ (e.g. tit‐for‐tat (TFT)‐like strategy), rather grooming is a commodity which can be bartered against female reproductive information or matings.

Way-marking behaviour: an aid to spatial navigation in the wood mouse (Apodemus sylvaticus)

“…This lack of significant difference between the sexes applied when contact ( p = 0.322) and non-contact ( p = 0.237) behaviours were treated separately. However, during inter-sexual interactions, the male and female interacting subjects did differ significantly in the rates at which they groomed ( p = 0.016) and sniffed ( p = 0.036) each other (this asymmetry is in accord with our earlier work [16]). Frequencies of agonistic behaviour patterns were too low (for both sexes) for analysis in our model.…”

Individual variation evades the Prisoner's Dilemma

“…Certainly, with all the intense research and enthusiastic application of PD to real world situations, we may expect that we should have observed more convincing empirical support by now if it ever were to hold as a paradigm befitting to it's immense theoretical appeal. We suggest that the concept of biological markets provides a good alternative framework for modelling variable games [1,17,28,38]. At the least, future studies should justify the assumption of zero payoff variation, given the importance of its implications.…”

A guide to practical babooning: Historical, social, and cognitive contingency

“…Finally, work on long-tailed macaques also has identified mating markets where males and females trade grooming and sex. 35 Given similar findings on wood mice, 36 cleaner fish, 37 suricates, 38 red bishop birds, 39 and micorhyzza, 40 the predictive power of the market approach underscores the need to take contingency seriously, not only at the evolutionary level but also in the interpretation of real-time social dynamics.…”