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predicting the probability of joining behaviour and competitive exclusion associated with joining.
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When foraging in a social group, individuals are faced with the choice of sampling their environment directly or exploiting the discoveries of others. The evolutionary dynamics of this trade-off have been explored mathematically through the producer-scrounger game, which has highlighted socially exploitative behaviours as a major potential cost of...
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... the patch scale, joining behaviour was common regardless of social rank (Table 1; Fig. 1A), consistent with our predictions. Although there was some increase in joining with social dominance in adults, even the lowest ranked individuals entered occupied patches approximately 55% (95% confidence intervals: 41% and 67%) of the time. ...Context 2
... our results reflect support for the three possible two-way interactions between spatial scale, dominance rank, and age class (Table 1). Our lack of support for a three-way interaction between these effects (likelihood ratio test: χ 2 = 0.70, p = 0.41) reflects the fact that there was some increase in joining with social rank in adults at both spatial scales. ...Similar publications
This study aimed to highlight the options selected by Campbell's monkey (Cercopithecus campbelli) to optimize foraging in the Taï National Park, Côte d'Ivoire. A group of C. campbelli, habituated to human's presence, was followed for two months in the dry season to test whether the three parameters (the distance traveled to reach the foraging sites...
Citations
... Dominance hierarchies, in which individuals' position reflects their competitive ability relative to other groups members, are a consistent feature of many animal societies (e.g., Bush et al., 2016;Grosenick et al., 2007;Shizuka & McDonald, 2015;Strauss et al., 2022;Strauss & Holekamp, 2019;Tibbetts & Dale, 2004). Social dominance is often associated with priority access to resources, such as food (Clutton-Brock et al., 1984;Lee & Cowlishaw, 2017;Robbers et al., 2021) or mates (Chen et al., 2011;Smith, 1993;Wroblewski et al., 2009). Hierarchy position also likely influences foraging behavior because rank is associated with different energetic demands (Castro et al., 2006;Killen et al., 2014). ...
Plastic pollution threatens almost every ecosystem in the world. Critically, many animals consume plastic, in part because plastic particles often look or smell like food. Plastic ingestion is thus an evolutionary trap, a phenomenon that occurs when cues are decoupled from their previously associated high fitness outcomes. Theory predicts that dominance hierarchies could dictate individual responses to evolutionary traps across social environments, but the social dimension of evolutionary trap responses has rarely been investigated. We tested how variation in group size influences the formation of dominance relationships and, in turn, how these dominance relationships drive differences in foraging behavior in Western mosquitofish (Gambusia affinis). This included foraging for a variety of familiar and novel food‐like items, including microplastics. Overall, dominant individuals were often the first to sample food and had higher bite rates than subordinates, including when foraging for microplastics. Importantly, how dominance affected foraging behavior depended on group size and on whether groups were presented with familiar or novel foods. Furthermore, individuals were consistent in their foraging behavior across trials with different group sizes, indicating the formation of stable social roles. These results suggest that predicting the ecological and evolutionary consequences of evolutionary traps will require an understanding of how social structures influence trap susceptibility.
... Second, phenotypic differences can predispose some individuals to one tactic, and ongoing work is attempting to identify generalized associations between traits and producing or scrounging. In some systems, larger or more dominant individuals tend to scrounge, because they are better able to displace others at the food resource [11][12][13]. In other systems, dominants produce more, perhaps because this tactic is high-reward but costly or impossible for subordinates to do [14,15]. ...
... Much of the empirical work to date involves controlled conditions in which novel producer-scrounger games are generated through experimental feeding (e.g. [10,[20][21][22]; but see [13,23,24]). These experiments elegantly test the predictions of theoretical models, but their simulated foraging scenarios do not necessarily reflect producerscrounger dynamics in nature. ...
Foraging animals commonly choose whether to find new food (as ‘producers’) or scavenge from others (as ‘scroungers’), and this decision has ecological and evolutionary consequences. Understanding these tactic decisions is particularly vital for naturally occurring producer–scrounger systems of economic importance, because they determine the system's productivity and resilience. Here, we investigate how individuals' traits predict tactic decisions, and the consistency and pay-offs of these decisions, in the remarkable mutualism between humans (Homo sapiens) and greater honeyguides (Indicator indicator). Honeyguides can either guide people to bees’ nests and eat the resulting beeswax (producing), or scavenge beeswax (scrounging). Our results suggest that honeyguides flexibly switched tactics, and that guiding yielded greater access to the beeswax. Birds with longer tarsi scrounged more, perhaps because they are more competitive. The lightest females rarely guided, possibly to avoid aggression, or because genetic matrilines may affect female body mass and behaviour in this species. Overall, aspects of this producer–scrounger system probably increase the productivity and resilience of the associated human–honeyguide mutualism, because the pay-offs incentivize producing, and tactic-switching increases the pool of potential producers. Broadly, our findings suggest that even where tactic-switching is prevalent and producing yields greater pay-offs, certain phenotypes may be predisposed to one tactic.
... Applications of the game to ecological data strongly support it [42,44,46], and highlight several factors that shape P-S interactions and the choice of strategy by individuals. Much evidence derives from studies of birds, as many species obtain discrete food packages that can easily be stolen, but studies of mammals also provide support [47,48]. ...
There is growing concern with social disparities in health, whether relating to gender, ethnicity, caste, socio-economic position or other axes of inequality. Despite addressing inequality, evolutionary biologists have had surprisingly little to say on why human societies are prone to demonstrating exploitation. This article builds on a recent book, ‘The Metabolic Ghetto’, describing an overarching evolutionary framework for studying all forms of social inequality involving exploitation. The dynamic ‘producer-scrounger’ game, developed to model social foraging, assumes that some members of a social group produce food, and that others scrounge from them. An evolutionary stable strategy emerges when neither producers nor scroungers can increase their Darwinian fitness by changing strategy. This approach puts food systems central to all forms of human inequality, and provides a valuable lens through which to consider different forms of gender inequality, socio-economic inequality and racial/caste discrimination. Individuals that routinely adopt producer or scrounger tactics may develop divergent phenotypes. This approach can be linked with life history theory to understand how social dynamics drive health disparities. The framework differs from previous evolutionary perspectives on inequality, by focussing on the exploitation of foraging effort rather than inequality in ecological resources themselves. Health inequalities emerge where scroungers acquire different forms of power over producers, driving increasing exploitation. In racialized societies, symbolic categorization is used to systematically assign some individuals to low-rank producer roles, embedding exploitation in society. Efforts to reduce health inequalities must address the whole of society, altering producer–scrounger dynamics rather than simply targeting resources at exploited groups.
... While captive house sparrows, Passer domesticus (Barnard & Sibly, 1981), and great tits, Parus major (Aplin & Morand-Ferron, 2017), may in fact present a relatively fixed strategy use, individuals of other species alternate between the PeS strategies in response to environmental changes (e.g. chacma baboons, Papio ursinus: King et al., 2009;Lee & Cowlishaw, 2017; spice finches, Lonchura punctulata: Coolen, 2002;Morand-Ferron, Varennes et al., 2011;Morand-Ferron, Wu et al., 2011). ...
... Most of these experiments have been conducted on captive birds (Afshar et al., 2015;Giraldeau & Livoreil, 1998;Morand-Ferron, Varennes et al., 2011). Research on wild animals, including primates (mammals with variable social systems), is still particularly scant (Di Bitetti & Janson, 2001;King et al., 2009;Lee & Cowlishaw, 2017). Moreover, few studies have analysed the adjustment process that occurs via learning in response to environmental conditions (Afshar et al., 2015;Belmaker et al., 2012;. ...
Animals that forage in groups may either search actively for food sources (producers, P) or monitor other members of the group in an attempt to consume resources that producers have encountered (scroungers, S). One factor that may influence the choice of foraging strategy is the finder's share, defined as the proportion of the resource consumed by the producer before the arrival of scroungers. Several models predict that when the finder's share is relatively small, the frequency of scrounging will be high because producing gives only a small benefit compared to playing scrounger. A model based on a linear operator learning rule confirmed this prediction and further predicted that individuals would change their foraging strategy gradually in response to environmental changes. We tested these predictions in an experiment involving three groups (N = 18 individuals) of free-ranging black-tufted marmosets, Callithrix penicillata. We manipulated the finder's share at artificial feeding stations by controlling the distribution of food rewards (slices of banana) among baited platforms. We divided our field experiments into two conditions – low finder's share (few food-rich patches) and high finder's share (many food-poor patches). Most (15/18) marmosets consumed more banana slices as scroungers in the low finder’s share condition than in the high finder’s share condition, as expected by the theory. However, individuals did not modify their frequency of use of the strategies in both conditions and did not show gradual learning as expected by the linear operator learning rule. We suggest that in social groups with high levels of tolerance and cooperation, such as those of marmosets, scrounging individuals can have higher foraging success without increasing their searching effort by sharing productive food patches with producers and other scroungers.
... The effects of social status are expected to be most pronounced when resources are clumped and defendable (for reviews see Giraldeau & Dubois, 2008;Grant, 1993;van Schaik, 1989). Studies with primates (King, Isaac, & Cowlishaw, 2009;Lee & Cowlishaw, 2017;Whitten, 1983) have shown that dominants have greater feeding success (i.e. obtain more food) when patches are rich and clumped. ...
Among social foragers, individuals can actively search for and find food (the producers) or join already discovered food patches (the scroungers). Compared to scroungers, producers often occupy more dangerous outer spatial positions in the group, but they benefit from the finder's advantage, which is the amount of food eaten before the arrival of others. Scroungers may occupy safer positions but they face feeding competition when joining a patch already occupied by others. Here, we report factors influencing intragroup spatial position, feeding strategies and feeding success for a group of wild vervet monkeys, C. pygerythrus, at Lake Nabugabo, Uganda. We collected data using behavioural observations and field experimentation (N = 132 trials) where we set up an artificial food patch with dispersed food rewards. We found that individuals who spent more time in the front-outer position of a moving group produced more. Producers that had a greater finder's time advantage (fed undetected by group members for longer periods) had a greater finder's advantage (consumed more food items before the arrival of other group members), and scroungers that arrived earlier had greater overall feeding success. We found that when the scrounger was higher ranking than other individuals at the patch, they used displacement scrounging (supplanted at least one individual from the patch to gain access to the food resource). However, feeding success did not differ between displacement scrounging and tolerated scrounging (when the scrounger fed at the patch with at least one other individual). Interestingly, we did not find higher-ranking individuals to have greater feeding success than lower-ranking individuals. Our findings corroborate previous studies showing that even among species with a linear dominance hierarchy and high occurrences of within-group contest competition, dominant individuals do not benefit from feeding advantages at large, dispersed food patches since they cannot monopolize the resource. Furthermore, our results emphasize the need to understand factors influencing feeding tolerance, particularly for subordinate individuals, who need to process ecological and social elements to maximize their food acquisition.
... Social hierarchy is common feature of group-living species, and its importance in determining an individual's competitive ability as a forager is well-established (Waite and Field 2007). For example, in studies on surfperch (Embiotoca lateralis) (Holbrook & Schmitt 1992), zenaida doves (Zenaida aurita) (Sol et al. 2005) and chacma baboons (Papio ursinus; Marshall et al. 2012, Lee & Cowlishaw 2017 dominant individuals had priority of access to the best quality food patches, while the subordinates had limited or no access. These differences in individuals' ability to access resources would be expected to lead to differences in individuals' diets and, potentially, their level of foraging specialisation (Sol et al. 2005;Araújo et al. 2011). ...
... Some wolves were found to shift to heavily marine-based diet during the autumn, whilst the majority of other individuals did not exhibit seasonal diet shifts (Darimont & Reimchen 2002). There is reason to expect that these effect of seasonality on foraging specialisation interact with potential effects of social rank, since the effect of rank on access to food resources is often dependent on environmental conditions (Stillman et al, 2002;Vahl et al. 2005;Marshall et al. 2012;Lee & Cowlishaw 2017). In particular, where resources are more defendable rank more strongly determines an individual's ability to access food resources Lee & Cowlishaw 2017). ...
... There is reason to expect that these effect of seasonality on foraging specialisation interact with potential effects of social rank, since the effect of rank on access to food resources is often dependent on environmental conditions (Stillman et al, 2002;Vahl et al. 2005;Marshall et al. 2012;Lee & Cowlishaw 2017). In particular, where resources are more defendable rank more strongly determines an individual's ability to access food resources Lee & Cowlishaw 2017). ...
Reproductive seasonality refers to the periodic temporal clustering of reproductive events in the annual cycle. It is often adaptive, because synchronizing the costliest stage of the female reproductive cycle with the most productive season can enhance maternal and offspring conditions and survival. Most studies investigating the evolutionary determinants of reproductive seasonality were done on fast-lived species from temperate habitats, while little is known for long-lived tropical species. In this thesis, we investigated the evolutionary determinants and fitness consequences of reproductive seasonality in two wild primate populations: non-seasonal breeding chacma baboons (Papio ursinus) from the seasonal and arid Namibian savannah and seasonal breeding mandrills (Mandrillus sphinx) from the Gabonese equatorial forest. Using a combination of long-term life history, morphological, behavioural and climatic data, we first reveal that despite their omnivorous diet and tropical habitats, mandrills and baboons are both subject to important seasonal variation in food availability, mainly caused by rainfall fluctuations. Consequently, we find that matching the peak of lactation with the seasonal food peak enhances female future reproduction (i.e. maternal reproductive pace) in both populations. We further show that two distinct optimal birth timing in chacma baboons maximise either maternal reproductive pace or offspring survival, by matching early versus late weaning with the seasonal food peak, respectively. The occurrence of multiple optimal birth timings weakens the strength of reproductive seasonality. In contrast, mandrill females do not face a similar trade-off between current and future reproduction over birth timing, and maximise their fitness by giving birth seasonally. In these two social species, we further find social effects on reproductive synchrony and seasonality. In chacma baboons, rank-related reproductive suppression leads to birth asynchrony and contributes to explain the absence of seasonal reproduction. In mandrills, dominant females are less seasonal than subordinates. Lastly, a comparative analysis on 16 populations from 7 species of wild baboons and relatives show unusually flexible patterns of reproductive phenology – with seasonal and non-seasonal breeding populations in a same species – and climatic unpredictability acts as a major driver of the loss of reproductive seasonality. Altogether, this work extends our understanding of the diverse patterns of reproductive seasonality observed in long-lived tropical species, by shedding light on previously overlooked determinants of reproductive phenology, such as climatic predictability, life history traits and trade-offs, and various social factors likely to affect other long-lived and social species.
... It is possible there are some 624 motivational aspects related to scrounging in each of the stages of task participation. For 625 example, individuals with a high propensity for social information may be less likely to 626 approach novel objects because they already have greater opportunity to exploit resources 627 using social cues, but if they do, they can afford to spend time exploring as these individuals 628 commonly hold high-ranking positions within a group (Lee & Cowlishaw, 2017). 629 ...
Despite the controlled testing conditions that are typical of captive environments, many evaluations of animal cognition fail to ensure that all tested individuals participate. This is even more evident under wild conditions, as animals are not restricted in their movement or social interactions and have other activities available. In this study, we aimed to understand variation in cognitive task participation in wild chacma baboons, Papio ursinus. We quantified individual differences in the latency and likelihood to approach and explore two types of stimuli for two cognitive tests: a set of coloured paper bags (in an associative learning test) and a blue cardboard square (in a second-order conditioning test). We evaluated whether participation in each task was predicted by individuals’ phenotypic traits/states, as well as by two additional aspects of their behaviour: (1) the availability of competing activities at the time of testing and (2) their propensity to exploit social information. We found consistent results for both types of stimuli regarding the effect of age: juveniles were more likely to contact the stimuli and explore them for longer. Similarly, for both tasks, individuals involved in an activity at the time of testing were less likely to contact the stimuli and had a lower exploration time. Finally, juveniles and females with a high propensity to use social information (i.e. scrounge) were more likely, and had shorter latencies, to contact the paper bags. Our findings not only highlight the potential bias cognitive studies conducted in the wild can have, but also some of the individual attributes and external factors that determine task participation.
... In other systems, scroungers aggressively appropriate resources (e.g. Lee & Cowlishaw, 2017) and in this case aggressive individuals would act as scroungers. ...
Consistent individual tendencies in behaviour, or behavioural types, are likely to impact the dynamics and outcomes of animal‐mediated seed dispersal. We review the extant literature on this issue and outline a conceptual overview to guide this emerging field. We provide an overview of possible ways in which behavioural types can affect animal‐mediated seed dispersal. We summarize theoretical mechanisms linking behavioural types with seed dispersal outcomes and review how behavioural types might affect each stage of seed dispersal, beginning with fruit encounter and harvest, and ending with events that take place after seed deposition.
Since behavioural types involve correlations among different behaviours (i.e. behavioural syndromes), they can generate unexpected associations between different decisions that are involved in seed dispersal, with conflicting (or reinforcing) effects on different stages of seed dispersal. Thus, we draw particular attention to trade‐offs faced by seeds dispersed by individuals with different behavioural tendencies. We also note that since seed dispersal is a multiplicative process with different stages, disperser behavioural types that provide moderately efficient dispersal at each stage will be better for plants than behavioural types that are very efficient at some steps, but inefficient on others. Finally, we provide testable predictions on the links between behavioural types and characteristics of seed dispersal, including, for example, influences on the probability of seed harvest, dispersal distance, deposition sites and condition of dispersed seeds.
We argue that investigating the links between behavioural types and animal‐mediated seed dispersal will provide a better mechanistic understanding of seed dispersal and plant regeneration.
A free plain language summary can be found within the Supporting Information of this article.
... For example, mutual interference, whereby agonistic encounters amongst predators result in individual predators being excluded from prey or suffering reduced feeding rates (MacLeod and Valiela 1975, Finke and Denno 2003, Stier et al. 2013, Schmidt et al. 2014, is often observed and is generally expected to increase with predator abundance (Delong andVasseur 2011, Schmidt et al 2014). Additionally, many predators are social and live in groups organised into dominance hierarchies (Tilson andHamilton 1984, Solomon andFrench 1997), and these hierarchies could affect the expression of predatory behaviours because rank is a determinant of foraging success (Baker et al. 1981, Dorning and Harris 2017, Lee and Cowlishaw 2017 and social conflict within predator hierarchies could influence individual predation effort and success. In fact, social conflict in unstable hierarchies may lead to mutual interference (MacLeod and Valiela 1975). ...
Understanding the determinants and consequences of predation effort, success and prey responses is important since these factors affect the fitness of predators and prey. When predators are also invasive species, the impacts on prey can be particularly far‐reaching with ultimate ecosystem‐level consequences. However, predators are typically viewed as behaviourally fixed within this interaction and it is unclear how variation in predator social dynamics affects predator–prey interactions. Using the invasive eastern mosquitofish Gambusia holbrooki and a native glass shrimp Paratya australiensis in Australia, we investigated how varying levels of social conflict within predator groups influences predator–prey interactions. By experimentally manipulating group stability of G. holbrooki, we show that rates of social conflict were lower in groups with large size differences, but that routine metabolic rates were higher in groups with large size differences. Predation effort and success did not vary depending on group stability, but in stable groups predation effort by aggressive dominants was greater than subordinates. The anti‐predator responses of prey to the stability of predator groups were mixed. While more prey utilized shelters when exposed to stable compared to unstable groups of predators, a greater proportion were sedentary when predator groups were unstable. Overall, this study demonstrates predator group stability is modulated by differences in body size and can influence prey responses. Further, it reveals a hidden metabolic cost of living in stable groups despite reduced overt social conflict. For invasive species management, it is therefore important to consider the behavioural and physiological plasticity of the invasive predators, whose complex social interactions and metabolic demands can modulate patterns of predator–prey interactions.
... It has been suggested that individuals can be forced to be cohesive because of constraints, such as a lack of available territories or resources; individuals then join groups to gain access to resources (Gaston 1978;Schoepf and Schradin 2012). This is tolerated by the dominant individuals controlling these resources because of the advantages brought by additional group members, such as lowered risk of predation or the ability to use subordinates as 'food-finders' (Gaston 1978;Hegner 1985;Clifton 1991;Stahl et al. 2001;Liker and Barta 2002;Roth II et al. 2008;Jolles et al. 2013;Lee and Cowlishaw 2017). Subordinates gain access to resources and the potential to one day become dominant and gain control over the resources themselves (Eberhard 1975;Wiley et al. 1999). ...
Many animals form social groups, but the adaptive value of being gregarious often differs between individuals. It has been suggested that individuals who gain fewer benefits may only join groups due to constraints on resources. These individuals would prefer to associate loosely with a group, associate strongly with a few preferred individuals and avoid despotic individuals. Alternatively, if joining a group is the optimum decision due to advantages gained from cohesion, individuals may exhibit decreased preferences regarding with whom they associate. We tested these ideas by analysing the social networks of wild winter groups of black-capped chickadees (Poecile atricapillus) in relation to experimental manipulation of resource distribution: three feeders 5 m apart (individuals can maintain contact with the group while also following their social preferences), 40 m apart (increased risk of losing contact while following preferences) and 130 m apart (extremely difficult to follow preferences without losing cohesion). If preferential associations are more important than cohesion, we predicted fewer but stronger connections with decreasing distance between feeders. Dynamic network analysis revealed that distance treatments did change the number of above average strength associations. However, stability of individual centrality was found to decrease when resources were close together and network structure remained similar overall. This suggests individuals maintain cohesion even when alternative foraging choices are available nearby but associate more selectively when given the opportunity. Our results indicate that while individuals will attempt to follow their preferential associations where possible, these are insufficient to cause breakdown in cohesion, possibly due to costs of losing contact with the group.
Significance statement
Animals must compromise between associating with preferred individuals and following group consensus. The importance of social preferences can help infer animals’ reasons for joining a group. If group cohesion brings benefits, following group consensus may be more important than individuals’ social preferences. Alternatively, if groups form simply due to lack of resources, following social preferences may be more important than maintaining group cohesion, depending on the costs of losing contact with the group. We examined this by looking at social network structure of black-capped chickadees in relation to resource distribution, expecting changes in network structure as it became easier or harder to exhibit social preferences. We found individuals had fewer strong associations when resources were closer, meaning that networks were more differentiated than when resources were further apart. This suggests that individuals associated more selectively when possible, though this did not appear to change overall network structure.
