Individual behavioural traits not social context affects learning about novel objects in archerfish

Abstract

Learning can enable rapid behavioural responses to changing conditions but can depend on the social context and behavioural phenotype of the individual. Learning rates have been linked to consistent individual differences in behavioural traits, especially in situations which require engaging with novelty, but the social environment can also play an important role. The presence of others can modulate the effects of individual behavioural traits and afford access to social information that can reduce the need for ‘risky’ asocial learning. Most studies of social effects on learning are focused on more social species; however, such factors can be important even for less-social animals, including non-grouping or facultatively social species which may still derive benefit from social conditions. Using archerfish, Toxotes chatareus, which exhibit high levels of intra-specific competition and do not show a strong preference for grouping, we explored the effect of social contexts on learning. Individually housed fish were assayed in an ‘open-field’ test and then trained to criterion in a task where fish learnt to shoot a novel cue for a food reward—with a conspecific neighbour visible either during training, outside of training or never (full, partial or no visible presence). Time to learn to shoot the novel cue differed across individuals but not across social context. This suggests that social context does not have a strong effect on learning in this non-obligatory social species; instead, it further highlights the importance that inter-individual variation in behavioural traits can have on learning. Significance statement Some individuals learn faster than others. Many factors can affect an animal’s learning rate—for example, its behavioural phenotype may make it more or less likely to engage with novel objects. The social environment can play a big role too—affecting learning directly and modifying the effects of an individual’s traits. Effects of social context on learning mostly come from highly social species, but recent research has focused on less-social animals. Archerfish display high intra-specific competition, and our study suggests that social context has no strong effect on their learning to shoot novel objects for rewards. Our results may have some relevance for social enrichment and welfare of this increasingly studied species, suggesting there are no negative effects of short- to medium-term isolation of this species—at least with regards to behavioural performance and learning tasks.

Looking beyond the Shoal: Fish Welfare as an Individual Attribute

“…While less is known about cognition in fishes than in mammals, the field is growing. Fish are capable of all the main kinds of learning identified in mammals [ 78 , 79 , 80 , 81 , 82 , 83 ], with individual differences in learning capacity [ 74 , 84 , 85 , 86 , 87 ] and possible relationships with personality. Looking at the relationship between the shy-bold continuum and learning, research has shown, for example, that shy brook trout were better at learning to navigate a maze than were bold brook trout [ 88 ], that bold sea trout were better at learning to avoid parasites [ 89 ], and that bold zebrafish and guppies showed better inhibition in a tube task [ 90 ].…”

Prosocial behavior in competitive fish: the case of the archerfish

“…Indeed, previous studies have demonstrated that archerfish can learn complex sensorimotor skills simply by observing the actions of other group members, without the need to practice themselves 42 . Some studies 48 even found that archerfish are sensitive to the presence of an audience while foraging (e.g., the audience has an impact on how long it takes archerfish to shoot, but also see 49 , which did not find any effect of the social context on archerfish learning rates). Establishing whether the competitive archerfish exhibit prosocial behavior could shed light whether even a competitive species, with no grouping preference 34 , would demonstrate this kind of behavior.…”

Tradition and invention: The bifocal stance theory of cultural evolution

“…For example, in European starlings (Sturnus vulgaris), dominant individuals are less neophobic and thus learn a novel task quicker than subordinate group members (Boogert, Reader, & Laland, 2006) while in jackdaws (Corvus monedula), dominant individuals are far more likely to monopolize resources leaving little opportunity for subordinates to learn individually (Federspiel, Boeckle, von Bayern, & Emery, 2019). However, in archerfish (Toxotes chatareus), only the personalities of individuals predict their learning propensity and not the social ranks (Jones, Spence-Jones, Webster, & Rendell, 2021). Within an individual, the choice between asocial learning, social learning, and innovation is flexible.…”