Learning performance is influenced by the social environment in cichlid fishes.

Abstract

It has been hypothesised that some specialised cognitive abilities may have evolved because of the challenges of living in complex social environments. Therefore, more-social species might be able to learn faster than less-social species. The aim of this study was to develop a learning framework to test how more- and less-social Lamprologine cichlid fishes perform across associative learning tasks. These cichlids are a group of closely related species with similar ecologies and life histories but varying degrees of sociality, making them an ideal group for comparative learning studies. We found that three nongrouping cichlids ( Telmatochromis temporalis, Lamprologus meleagris , and Neolamprologus tretocephalus ) outperformed three closely related highly social, cooperatively breeding cichlids ( N. pulcher, N. multifasciatus , and Julidochromis dickfeldi ) on an associative learning task based on food rewards. However, we hypothesised that these differences may be caused by the social environment during testing and might not reflect true cognitive differences. Indeed, when we drilled down and compared just two species across four different social conditions, we found that the social environment during learning trials affected the performance of the highly social N. pulcher and the less-social T. temporalis differently. We then performed further experiments with both N. pulcher and T. temporalis under more natural social settings. Under these more natural social conditions, we found that N. pulcher learned to differentiate accessible and inaccessible shelters faster than T. temporalis . These findings highlight the potential for expanding comparative experiments investigating the relationship between sociality and cognition and emphasise the crucial role social environment plays in learning outcomes.

The ram cichlid (Mikrogeophagus ramirezi) learns an associative task: a new fish species for memory research

“…Zebrafish as well as other fish species have been found to acquire memory of CS–US association 11 – 13 , 16 , 17 , 22 , 40 , 48 , 49 . However, the studies in which such learning/memory performance was demonstrated with these fish species often required larger number of training trials and more subjects than employed in the current study.…”

“…For example, African cichlids have been studied for neophobia and learning performance 15 , and spatial learning has been demonstrated in other cichlid species 16 . The effect of social environment on learning has also been studied in cichlids 17 . Guppies have been used to test learning and memory and underlying neuroplastic changes in the brain 18 as well as for brain morphology correlates 19 .…”

“…Last, we note that species that belong to the family Cichlidae are generally considered among the most “intelligent” fish species both in the aquarium hobby 38 and in the scientific literature 39 – 41 . Although the ram cichlid has not been employed in learning studies, it is known to possess a sophisticated behavioural repertoire that implies good cognitive and mnemonic abilities 15 – 17 , 20 , 42 , 43 . For example, unlike the zebrafish, it is a bi-parental cichlid that raises its young, protects its territory, and stays in pairs, implying sophisticated intra-specific communication, spatial memory as well as recognition of individuals.…”

Unifying psychological and biological approaches to understanding animal cognition.

“…Salena and Balshine (2020), Stanbrook, Jodoin, Culbert, Shultz, & Balshine (2020), and Berhane and Gazes (2020) test the relation between sociality and cognition. The former two papers take a comparative, among-species approach, while the latter examines variation among individual variation.…”

Meta-analyses reveal support for the Social Intelligence Hypothesis

“…The relationship between group size and brain size/neocortex size in anthropoid primates has since been replicated in several other studies (Dunbar, 1995; Barton, 1996; Walker et al ., 2006; Dunbar & Shultz, 2007), which inevitably led to the expansion of the SIH beyond primates. Since its inception, support for the SIH has been found in various species of mammals (Wang et al ., 2018; Johnson-Ulrich & Holekamp, 2020; Fox, Muthukrishna & Shultz, 2017; Sakai et al ., 2011; Dunbar & Bever, 1998; Borrego & Gaines, 2016), birds (Beauchamp & Fernández-Juricic, 2004; Kulahci et al ., 2016; Langley et al ., 2018 b ; Aplin et al ., 2012; Boogert, Farine & Spencer, 2014; Morand-Ferron & Quinn, 2011; Lipkind et al ., 2002; Ashton et al ., 2018 a ; Speechley et al ., 2024), fish (Fischer et al ., 2015; Triki et al ., 2019; Brandão, Braithwaite & Goncalves-de-Freitas, 2015; Stanbrook et al ., 2020; Leris & Reader, 2016; Ausas et al ., 2019), and invertebrates (Liedtke & Schneider, 2017; Kamhi et al ., 2016; Ott & Rogers, 2010; Amador-Vargas et al ., 2015; Seid & Junge, 2016). However, support for the SIH has not been consistent among or within taxa (Templeton, Kamil & Balda, 1999; Iwaniuk & Arnold, 2004; Kverková et al ., 2018; Forss et al ., 2016; DeCasien et al ., 2017; Fedorova, Evans & Byrne, 2017), with many papers reporting conflicting results, even within the same species, depending on the metric of sociality or cognition used (Fox et al ., 2017; Kamhi et al ., 2016; Sakai et al ., 2016; Reader, Hager & Laland, 2011; DeCasien & Higham, 2019).…”