To determine whether the choice of client fishes in the cleaner fish Labroides dimidiatus was influenced by client size, cleaner fish were given a choice of equal amount of food spread on large and ...small client redfin butterflyfish Chaetodon trifasciatus models. All large models received bites from cleaners compared to 27% for small models. Seventy‐nine per cent of cleaners took their first bite from the large fish model. The results suggest that client size may affect cleaner fish choice.
Reef fish that actively visit cleaner fish to have parasites and dead or infected tissue removed face two potential problems: they might have to wait while cleaners inspect other clients, and ...cleaners might feed on healthy body tissue, a behaviour that is referred to as cheating. Individuals of some ‘client’ species have large home ranges, which cover several cleaning stations, while others have small territories or home ranges with access to only one cleaning station. The former can thus choose between cleaners, while the latter cannot. We investigated whether clients with large home ranges change cleaning partners to outplay cleaners against each other to achieve (1) priority of access over clients with no choice at cleaning stations and (2) control over cheating by cleaners. We followed individuals of longnosed parrotfish, Hipposcarus harid, for up to 120min in their natural environment and noted their interactions with cleaner wrasses, Labroides dimidiatus. Individuals were likely to return to the same cleaning station if the previous interaction had ended without conflict but changed cleaners for the next inspection if they had been either cheated or ignored, at least if the time between two consecutive visits was short. The overall attractiveness of a cleaning station seemed to be largely independent of service quality, which appeared to be similar at all stations. This is the first empirical evidence that the option to change partners is used as a control mechanism to stabilize cooperative behaviour.
Parasites with complex life cycles often change intermediate host traits in order to enhance their transmission to the next host. Acanthocephalans are excellent examples of such parasitic ...manipulation. Here, we summarise evidence for adaptive parasitic manipulation in this group, provide a comprehensive overview of intermediate host traits affected by these parasites and discuss critical items for parasitic manipulation such as avoidance of infected prey by target hosts and transmission to dead‐end hosts.
Intraspecific cooperation and interspecific mutualism often feature a marked asymmetry in the scope for exploitation. Cooperation may nevertheless persist despite one‐sided opportunities for ...cheating, provided that the partner vulnerable to exploitation has sufficient control over the duration of interaction. Here we develop a simple, game theoretical model of this form of partner control. We show that as a victim's ability to terminate an encounter increases, selection can favour reduced exploitation, resulting in a switch from parasitism to mutualism. For a given level of control, exploitation is likely to be less intense and the interaction to last longer when there are greater mutualistic benefits to be gained, and when the benefits of cheating are lower relative to the costs inflicted on the victim. Observations of interactions between cleaner‐fish and non‐predatory species of client are shown to match these predictions.
Fish cognition: a primate's eye view Bshary, Redouan; Wickler, Wolfgang; Fricke, Hans
Animal cognition,
03/2002, Letnik:
5, Številka:
1
Journal Article
Recenzirano
Odprti dostop
We provide selected examples from the fish literature of phenomena found in fish that are currently being examined in discussions of cognitive abilities and evolution of neocortex size in primates. ...In the context of social intelligence, we looked at living in individualized groups and corresponding social strategies, social learning and tradition, and co-operative hunting. Regarding environmental intelligence, we searched for examples concerning special foraging skills, tool use, cognitive maps, memory, anti-predator behaviour, and the manipulation of the environment. Most phenomena of interest for primatologists are found in fish as well. We therefore conclude that more detailed studies on decision rules and mechanisms are necessary to test for differences between the cognitive abilities of primates and other taxa. Cognitive research can benefit from future fish studies in three ways: first, as fish are highly variable in their ecology, they can be used to determine the specific ecological factors that select for the evolution of specific cognitive abilities. Second, for the same reason they can be used to investigate the link between cognitive abilities and the enlargement of specific brain areas. Third, decision rules used by fish could be used as 'null-hypotheses' for primatologists looking at how monkeys might make their decisions. Finally, we propose a variety of fish species that we think are most promising as study objects.
Carnivorous animals are assumed to consume prey to optimise energy intake. Recently, however, studies using Nutritional Geometry (NG) have demonstrated that specific blends of macronutrients (e.g. ...protein, fat and in some cases carbohydrates), rather than energy per se, drive the food selection and intake of some vertebrate and invertebrate predators in the laboratory. A vital next step is to examine the role of nutrients in the foraging decisions of predators in the wild, but extending NG studies of carnivores from the laboratory to the field presents several challenges. Biologging technology offers a solution for collecting relevant data which when combined with NG will yield new insights into wild predator nutritional ecology.
In Ta National Park, Ivory Coast, humans with guns hunt monkeys for their meat. The poachers imitate animal calls to feign the presence of eagles or leopards, two predators to which monkeys react ...with high calling rates and approach. In the presence of humans, monkeys become silent and move off. A small area of the park is now avoided by poachers, due to the establishment of a field project on chimpanzees in 1979. This offered the opportunity to investigate whether sudden changes in predation pressure lead to a rapid alteration in prey behaviour. Playback experiments, using groups of Diana monkeys, Cercopithecus diana, as subjects, revealed that the poachers' strategy works well in the home range of the habituated chimpanzee group. However, monkeys which are frequently exposed to poachers are rarely fooled by the imitations. Adaptive discrimination abilities can thus be acquired or lost within the lifespan of individual monkeys.
Supply and demand largely determine the price of goods on human markets. It has been proposed that in animals, similar forces influence the payoff distribution between trading partners in sexual ...selection, intraspecific cooperation and interspecific mutualism. Here we present the first experimental evidence supporting biological market theory in a study on cleaner fish, Labroides dimidiatus. Cleaners interact with two classes of clients: choosy client species with access to several cleaners usually do not queue for service and do not return if ignored, while resident client species with access to only one cleaning station do queue or return. We used plexiglas plates with equal amounts of food to simulate these behaviours of the two client classes. Cleaners soon inspected ‘choosy’ plates before ‘resident’ plates. This supports previous field observations that suggest that client species with access to several cleaners exert choice to receive better (immediate) service.
Evolution of spite through indirect reciprocity Johnstone, Rufus A.; Bshary, Redouan
Proceedings of the Royal Society. B, Biological sciences,
09/2004, Letnik:
271, Številka:
1551
Journal Article
Recenzirano
Odprti dostop
How can cooperation persist in the face of a temptation to 'cheat'? Several recent papers have suggested that the answer may lie in indirect reciprocity. Altruistic individuals may benefit by ...eliciting altruism from observers, rather than (as in direct reciprocity) from the recipient of the aid they provide. Here, we point out that indirect reciprocity need not always favour cooperation; by contrast, it may support spiteful behaviour, which is costly for the both actor and recipient. Existing theory suggests spite is unlikely to persist, but we demonstrate that it may do so when spiteful individuals are less likely to incur aggression from observers (a negative form of indirect reciprocity).
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