Ronald Noë

Biological markets: supply and demand determine the effect of partner choice in cooperation, mutualism and mating

The formation of collaborating pairs by individuals belonging to two different classes occurs in the contexts of reproduction and intea-specific cooperation as well as of inter-specific mutualism. There is potential for partner choice and for competition for access to preferred partners in all three contexts. These selective forces have long been recognised as important in sexual selection, but their impact is not yet appreciated in cooperative and mutualistic systems. The formation of partnerships between members of different classes has much in common with the conclusion of trade agreements in human markets with two classes of traders, like producers and consumers, or employers and employees. Similar game-theoretical models can be used to predict the behaviour of rational traders in human markets and the evolutionarily stable strategies used in biological markets. We present a formal model in which the influence of the market mechanism on selection is made explicit. We restrict ourselves to biological markets in which: (1) Individuals do not compete over access to partners in an agonistic manner, but rather by outcompeting each other in those aspects that are preferred by the choosing party. (2) The commodity the partner has to offer cannot be obtained by the use of force, but requires the consent of the partner. These two restrictions ensure a dominant role for partner choice in the formation of partnerships. In a biological market model the decision to cooperate is based on the comparison between the offers of several potential partners, rather than on the behaviour of a single potential partner, as is implicitly assumed in currently accepted models of cooperation. In our example the members of one class A offer a commodity of fixed value in exchange for a commodity of variable value supplied by the other class, B. We show that when the B-class outnumbers the A-class sufficiently and the cost for the A-class to sample the offers of the B-class are low, the choosiness of the A-class will lead to selection for the supply of high value commodities by the B-class (Fig. 3a). Under the same market conditions, but with a high sampling cost this may still be the evolutionariy stable outcome, but another pair of strategies proves to be stable too: relaxed choosiness of class A coupled with low value commodities supplied by class B (Fig. 3b). We give a number of examples of mating, cooperative and mutualistic markets that resemble the low sampling cost situation depicted in Fig. 3a.

Diana monkey long-distance calls: Messages for conspecifics and predators

Abstract Primate long-distance calls have typically been interpreted as communication signals between conspecific groups (the ‘resource defence hypothesis’), but their potential role as anti-predator alarm calls has received comparably little attention. Male diana monkeys,Cercopithecus diana dianain the Tai forest of Cote d’Ivoire often utter long-distance calls, either spontaneously or in reaction to a variety of stimuli, including predators and non-predators. The present study focuses only on predation contexts and provides evidence for communication to both predators and conspecifics. Males called only in response to predators whose hunting success depends on unprepared prey, that is, leopards and crowned hawk eagles, but not in response to pursuit hunters, such as chimpanzees and humans, which can pursue the caller in the canopy. Calling was regularly combined with approaching the predator. Both observations suggest that male long-distance calls are used to signal detection to the predator (‘perception advertisement hypothesis’). Analysis of male long-distance calls given to leopards and eagles showed that they differed according to a number of acoustic parameters. The two call variants were played to different diana monkey groups; conspecifics responded to them as though the original predator were present. We conclude that, in addition to their function in perception advertisement, diana monkey long-distance calls function as within-group semantic signals that denote different types of predators.

Economics in Nature: Social Dilemmas, Mate Choice and Biological Markets

Preface 1. Games and markets: economic behaviour in humans and other animals Peter Hammerstein Part I. Economic Behavior in Social Networks: 2. Social dilemmas and human behaviour Elinor Ostrom 3. Cooperation and collective action in animal behaviour Charles Nunn and Rebecca J. Lewis 4. Conflict, reconciliation and negotiation in non-human primates: the value of long-term relationships Jan A. R. A. M Van Hooff Part II. Biological Markets: 5. Biological markets: partner choice as the driving force behind the evolution of mutualisms Ronald Noe 6. The utility of grooming in baboon troops Louise Barrett and Peter S. Henzi 7. The cleaner fish market Redouan Bshary 8. Modeling interspecific mutualisms as biological markets Jason D. Hoeksema and Mark W. Schwartz Part III. Mating Markets: 9. Human mate choice strategies Boguslaw Pawlowski and Robin I. M. Dunbar 10. How does mate choice contribute to exaggeration and diversity in sexual characters? Andrew Pomiankowski and Yoh Iwasa 11. Information about sperm competition and the economics of sperm allocation Geoffrey A. Parker and Mike A. Ball 12. The economics of male mating strategies Robin I. M. Dunbar.

Supply and demand determine the market value of food providers in wild vervet monkeys

Animals neither negotiate verbally nor conclude binding contracts, but nevertheless regularly exchange goods and services without overt coercion and manage to arrive at agreements over exchange rates. Biological market theory predicts that such exchange rates fluctuate according to the law of supply and demand. Previous studies showed that primates pay more when commodities become scarcer: subordinates groomed dominants longer before being tolerated at food sites in periods of shortage; females groomed mothers longer before obtaining permission to handle their infants when there were fewer newborns and males groomed fertile females longer before obtaining their compliance when fewer such females were present. We further substantiated these results by conducting a 2-step experiment in 2 groups of free-ranging vervet monkeys in the Loskop Dam Nature Reserve, South Africa. We first allowed a single low-ranking female to repeatedly provide food to her entire group by triggering the opening of a container and measured grooming bouts involving this female in the hour after she made the reward available. We then measured the shifts in grooming patterns after we added a second food container that could be opened by another low-ranking female, the second provider. All 4 providers received more grooming, relative to the amount of grooming they provided themselves. As biological market theory predicts, the initial gain of first providers was partially lost again after the introduction of a second provider in both groups. We conclude that grooming was fine-tuned to changes in the value of these females as social partners.

Red colobus and Diana monkeys provide mutual protection against predators

We tested the hypothesis that red colobus monkeys, Procolobus badius and Diana monkeys, Cercopithecus diana in Taï National Park, Ivory Coast, associate to increase safety from predation. We recorded stratum use, exposure and vigilance of each species in the presence and in the absence of the partner species. In the presence of Diana monkeys, red colobus used lower strata more often, were more exposed to the forest floor and looked down less often while foraging. This suggests that red colobus reduce predation pressure from ground predators by associating with Diana. There are several indications that both species are less vulnerable to birds of prey when associated: red colobus looked sideways less often and were more exposed to the front, Diana monkeys used greater heights and were more exposed to the front, to the rear and from above. We also asked whether specific sentinel qualities of Diana monkeys might explain why other sympatric monkey species additionally seek their presence. When groups of various species compositions were approached by an observer, or confronted with an eagle model, Diana monkeys raised the alarm in most cases. Since neither monkey species improves its foraging success when associated, this study shows that predation can both maintain and be the ultimate cause of interspecific associations.Copyright 1997 The Association for the Study of Animal Behaviour

A community-level evaluation of the impact of prey behavioural and ecological characteristics on predator diet composition.

Although predation avoidance is the most commonly invoked explanation for vertebrate social evolution, there is little evidence that individuals in larger groups experience lower predation rates than those in small groups. We compare the morphological and behavioural traits of mammal prey species in the Taï forest, Ivory Coast, with the diet preferences of three of their nonndash;human predators: leopards, chimpanzees and African crowned eagles. Individual predators show marked differences in their predation rates on prey species of different body sizes, but clear patterns with prey behaviour were apparent only when differences in prey habitat use were incorporated into the analyses. Leopard predation rates are highest for terrestrial species living in smaller groups, whereas eagle predation rates are negatively correlated with group size only among arboreal prey. When prey predation rates are summed over all three predators, terrestrial species incur higher predation rates than arboreal species and, within both categories, predation rates decline with increasing prey group size and decreasing density of groups in the habitat. These results reveal that it is necessary to consider anti–predator strategies in the context of a dynamic behavioural interaction between predators and prey.

HOW ADAPTIVE OR PHYLOGENETICALLY INERT IS PRIMATE SOCIAL BEHAVIOUR? A TEST WITH TWO SYMPATRIC COLOBINES

[Socio-ecological theories predict that females adapt their social behaviour to their environment. On the other hand, as a result of phylogenetic inertia, social behaviour may be slow to catch up when the environment changes. If social behaviour is adapted to the environment, competition and co-operation among females is predicted to reflect the characteristics of food sources. Contest competition both between and within groups is expected to result in alliances among related, philopatric, females. We compared social relationships and food characteristics of two sympatric and congeneric primate species, the red colobus and the black-and-white colobus of the Tai National Park, Ivory Coast. We found that affiliative interactions among females were comparable between the species. The differences in food characteristics could explain why black-and-white females competed more often than did red colobus females, both at the intra- and inter-group level. In contrast to socio-ecological theory, female inter-group aggression was not linked to female philopatry in black-and-white colobus. The species differed from each other and from other populations of the same or closely related species with respect to their inter-group behaviour which indicates that phylogenetic inertia did not constrain this aspect of social behaviour., Socio-ecological theories predict that females adapt their social behaviour to their environment. On the other hand, as a result of phylogenetic inertia, social behaviour may be slow to catch up when the environment changes. If social behaviour is adapted to the environment, competition and co-operation among females is predicted to reflect the characteristics of food sources. Contest competition both between and within groups is expected to result in alliances among related, philopatric, females. We compared social relationships and food characteristics of two sympatric and congeneric primate species, the red colobus and the black-and-white colobus of the Tai National Park, Ivory Coast. We found that affiliative interactions among females were comparable between the species. The differences in food characteristics could explain why black-and-white females competed more often than did red colobus females, both at the intra- and inter-group level. In contrast to socio-ecological theory, female inter-group aggression was not linked to female philopatry in black-and-white colobus. The species differed from each other and from other populations of the same or closely related species with respect to their inter-group behaviour which indicates that phylogenetic inertia did not constrain this aspect of social behaviour.]

Anti-predation behaviour of red colobus monkeys in the presence of chimpanzees

Abstract Predator-prey interactions are usually regarded as evolutionary “arms races”, but evidence is still scarce. We examined whether the anti-predation strategies of red colobus monkeys (Procolobus badius) are adapted to the hunting strategies of chimpanzees (Pan troglodytes) in the Taï National Park, Ivory Coast. Taï chimpanzees search for red colobus groups, approach them silently and hunt co-operatively. Our playback experiments and observations of natural encounters revealed that red colobus hid higher up the trees in positions where exposure to the forest floor is minimal and became silent, when chimpanzees were close. They moved away silently through the canopy, when chimpanzees were still at some distance. However, if a group of diana monkeys was nearby in the latter situation, red colobus sought their presence even if they had to move towards the chimpanzees. Chimpanzees refrained from hunting associated red colobus groups, probably because diana monkeys are excellent sentinels for predators approaching over the forest floor. Thus several elements of both the predators and the preys strategies correspond to each other. Finally, we compared the interactions between the two species in Taï and in Gombe, Tanzania. We suggest that the difference in size ratio between the two species at the two sites and adaptation of hunting techniques and of escape modes to different forest structures can explain why Gombe red colobus attack chimpanzees while Taï red colobus try to escape. We conclude that predator-prey interactions can indeed lead to evolutionary arms races, with the specific form of co-adaptations depending on environmental factors.

Waser’s Gas Model Applied to Associations between Red Colobus and Diana Monkeys in the Taï National Park, Ivory Coast

We performed a study on the association between a group of red colobus monkeys ( Colobus badius ) and a group of Diana monkeys ( Cercopithecus diana ) in the Tai Nati

The Monkeys of the Taï forest : an African primate community

1: The monkeys of the Tai Forest: an introduction W. S. McGraw and K. Zuberbuhler, Part I. Social Behavior: 2. The social system of guenons P. Buzzard and W .Eckardt 3: How small-scale differences in food competition lead to different social systems in three closely related sympatric colobines A. H. Korstjens, K. Bergman, C.Deffernez, M. Krebs, E. C. Nijssen, BAM van Oirschot, C Paukert, E. P. Schippers 4. The structure of social relationships among sooty mangabeys in Tai F. Range, T. Forderer, Y. Meystre, C. Benetton, and C. Fruteau Part II. Anti-Predation Strategies: 5. Interactions between leopard and monkeys K. Zuberbuhler and D. Jenny 6. Interactions between red colobus and chimpanzees R. Bshary 7. Interactions between African crowned eagles and their primate prey community S. Shultz and S. Thomsett 8. Semantic information in alarm calls K. Zuberbuhler Part III. Habitat Use: 9. Positional behavior and habitat use of Tai Forest monkeys W. S. McGraw Part IV. Conservation: 10. Can monkey behavior be used as an indicator for poaching pressure? A case study of the Diana guenon (Cercopithecus diana) and the western red colobus (Procolobus badius) I. Kone and J. Refisch 11. Vulnerability and conservation of the Tai Forest monkeys W. S. McGraw.