Cognition in narrow-striped mongooses, Mungotictis decemlineata, a Malagasy carnivore species
by Bako Nandrianina Rasolofoniaina
Date of Examination:2020-02-13
Date of issue:2021-02-11
Advisor:Prof. Dr. Peter M. Kappeler
Referee:Dr. Dietmar Zinner
Referee:Dr. Claudia Fichtel
Referee:Prof. Dr. Mark Maraun
Referee:PD Dr. Oliver Schülke
Referee:Dr. Tanya Behne
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Description:Doctoral dissertation
Abstract
English
Carnivores include a wide variety of species that differ in social organization and brain-size, but these two characteristics do not seem to be linked to each other. Additionally, previous studies found no evidence of relationship between social organisation and cognitive abilities in carnivores since solitary and social species exhibited similar cognitive performances. Therefore, the social intelligence hypothesis, which assumes that the demand for sociality influenced the increase in brain-size, was rejected to not explain the evolution of intelligence fully in carnivores. Besides, carnivores exhibit a diversity of ecological adaptations, by inhabiting a diverse type of habitat. Their challenging environment was assumed to have boosted the evolution of intelligence within this taxon, which is supported by the cognitive buffer hypothesis stating that larger brain size evolved in response to harsh environment. However, despite the great diversity found among carnivores in terms of socio-ecological characteristics, most studies on cognition focused on comparing species with similar habitat, not allowing disentangling the primary factor driving the evolution of cognition. Investigating the cognitive abilities of species that exhibit socio-ecological characteristics different to the species that have been addressed previously could help elucidate the evolution of carnivore cognition. Therefore, in this thesis, I provide new comparative data by examining the cognitive abilities of the narrow-striped mongooses (Mungotictis decemlineata), a Malagasy carnivores species, which is group living and inhabits a dry tropical forest. The aim of this thesis was to add data on the missing aspect of the existing studies on carnivores’ cognition so far and to test M. decemlineata in a range of cognitive traits covering domain-general cognition, social cognition, and physical cognition. An essential step in the investigation of the evolution of intelligence consists of evaluating individual differences in cognitive abilities and their underpinning proximate factors. For this, I investigated the factors underlying individual differences in cognitive performances. I assessed individuals’ cognitive abilities in a wild setting in an individually marked population of narrow-striped mongooses. The study was conducted in Kirindy Forest, Western Madagascar. From 2014 to 2017, to test cognitive abilities, I established a psychometric test battery whose tasks addressed cognitive traits involved in behavioural flexibility, inhibitory control, innovation problem-solving, social learning, and causal understanding. Additionally, to measure personality traits, I conducted novel object tests assessing individuals’ neophobia. In total, I could test depending on the experiment up to 33 narrow-striped mongooses. To maximise the possibility of testing the individuals, only female narrow-striped mongooses were considered in this study. Since female narrow-striped mongooses were tested in their home ranges in a group set-up, the effect of social learning on cognitive performances was also examined. I found that narrow-striped mongooses performed well in behavioural flexibility, innovative problem solving, social learning, and causal understanding. Additionally, inhibitory control promoted learning in narrow-striped mongooses. However, the effect of neophobia on individual performances differed between cognitive tasks. Neophobia did not covary with individuals’ performances during the behavioural flexibility experiments and problem-solving tasks. Whereas, in the social learning task, less neophobic individuals were better at solving the task. Possible explanation for the variability of the direction of the relationship between personality traits and cognitive performance might be that there are other related factors such as intrinsic factors underlying this relationship. Future studies should take into consideration these proximate factors when examining the relationship between personality traits and cognitive performance. Individuals utilised social information in order to switch the previously learned contingencies during the behavioural flexibility task. Additionally, the use of social information facilitated learning in the social learning task, and the presence of skilled individuals improved the learning of naïve individuals. This reliance of female narrow-striped mongooses on social learning appears to be related to the fact that they live in stable group and synchronise their activity continuously. In conclusion, M. decemlineata performed comparably in the addressed cognitive domains not only to meerkats (Suricata suricatta), a closely related African carnivore taxon, but also to other carnivore species, such as spotted hyenas (Crocuta crocuta), racoons (Procyon lotor), and wolves (Canis lupus). Thus with this study, I contributed to the investigation of cognition in carnivores by providing new comparative data. In the future, research should consider more interspecific comparisons, and studies should analyse the in-depth link between individuals’ cognitive abilities, natural behaviours, ecological and life-history factors, as well as fitness in order to understand fully how intelligence in carnivores evolved.
Keywords: cognition; carnivores; Mungotictis decemlineata; neophobia; inhibitory control; social information; behavioural flexibility; problem-solving; social learning; causal performance