Abstract: ABSTRACT Reciprocity is probably the most debated of the evolutionary explanations for cooperation. Part of the confusion surrounding this debate stems from a failure to note that two different processes can result in reciprocity: partner control and partner choice. We suggest that the common observation that group-living animals direct their cooperative behaviours preferentially to those individuals from which they receive most cooperation is to be interpreted as the result of the sum of the two separate processes of partner control and partner choice. We review evidence that partner choice is the prevalent process in primates and propose explanations for this pattern. We make predictions that highlight the need for studies that separate the effects of partner control and partner choice in a broader variety of group-living taxa.

Abstract: More than half a century has now elapsed since coalition or alliance formation theory (CAFT) was first developed. During that time, researchers have amassed a vast amount of detailed and high-quality data on coalitions or alliances among primates and other animals. But models have not kept pace, and more relevant theory is needed. In particular, even though CAFT is primarily an exercise in polyadic game theory, game theorists have devoted relatively little attention to questions that motivate field research, and much remains largely unexplored. The state of the art is both a challenge and an opportunity. In this review we describe a variety of game-theoretic and related modelling approaches that have much untapped potential to address the questions that field biologists ask.

Abstract: Neighboring territory owners are often less aggressive toward each other than to strangers (“dear enemy” effect). There is, however, little evidence for territorial defense coalitions whereby a neighbor will temporarily leave his/her own territory, enter that of a neighbor, and cooperate in repelling a conspecific intruder. This is surprising, as theoreticians have long posited the existence of such coalitions and the circumstances under which they should evolve. Here we document territorial defense coalitions in the African fiddler crab Uca annulipes, which lives in large colonies wherein each male defends a burrow and its surrounding area against neighbors and “floaters” (burrowless males). Fights between a resident and a floater sometimes involve another male who has left his territory to fight the floater challenging his neighbor. Using simple experiments, we provide the first evidence of the rules determining when territorial coalitions form. Our results support recent models that suggest that these coalitions arise from by‐product mutualism.

Abstract: Both white-tailed deer, Odocoileus virginianus, and mule deer, O. hemionus, females defend fawns against coyotes, Canis latrans, but only mule deer defend nonoffspring conspecific and heterospecific fawns. During a predator attack, females may have to decide whether to defend a fawn while having imperfect information on its identity obtained from hearing a few distress calls. Although imperfect recognition can influence altruistic behaviour, few empirical studies have considered this point when testing functional explanations for altruism. We designed a series of playback experiments with fawn distress calls to test alternative hypotheses (by-product of parental care, kin selection, reciprocal altruism) for the mule deer's defence of nonoffspring, specifically allowing for the possibility that females mistake these fawns for their own. White-tailed deer females approached the speaker only when distress calls of white-tailed deer fawns were played and when their own fawn was hidden, suggesting that fawn defence was strictly a matter of parental care in this species. In contrast, mule deer females responded similarly and strongly, regardless of the caller's identity, the female's reproductive state (mother or nonmother) or the presence of their own offspring. The failure of mule deer females to adjust their responses to these conditions suggests that they do not defend nonoffspring because they mistake them for their own fawns. The lack of behavioural discrimination also suggests that kin selection, reciprocal altruism and defence of the offspring's area are unlikely to explain the mule deer's defence of nonoffspring. We identify causal and functional questions that still need to be addressed to understand why mule deer defend fawns so indiscriminately.

Abstract: In the large majority of cases and circumstances, horses benefit from their association with man. However, abuse of horses can occur, due to neglect or through the pressures of competition. The welfare of all animals, including competition horses, has become increasingly topical over the past ten years. Equestrian sport is coming under closer public scrutiny due to reports of apparent abuse. The bodies responsible for regulating these sports strenuously endeavour to protect the welfare of horses which compete under their rules and regulations. The Federation Equestre Internationale (FEI: International Equestrian Federation) is the sole authority for all international events in dressage, show-jumping, three-day event, driving, endurance riding and vaulting. The FEI rules illustrate the ways in which the welfare of competing horses is safeguarded.