Perdedores e vencedores apresentam similar controle inibitório em um peixe ciclídeo
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Data
2021-11-10
Autores
Pereira, André Vitor Salinas
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Universidade Estadual Paulista (Unesp)
Resumo
Lutas intraespecíficas para definição e manutenção da hierarquia em animais sociais podem ser muito custosas aos competidores. Por isso, algumas estratégias comportamentais que reduzem esses custos foram selecionadas. Uma delas é histórico de lutas, cujos indivíduos com experiência de vitórias apresentam maior chance de lutar e vencer, enquanto indivíduos perdedores apresentam propensão a evitar ou perder as lutas subsequentes (efeito vencedor/perdedor). Isso requer uma certa habilidade cognitiva que permita ao indivíduo interpretar e tomar decisões no ambiente social, ajustando suas respostas conforme experiências passadas (flexibilidade cognitiva). No presente trabalho testamos a relação entre o efeito vencedor/perdedor e a flexibilidade cognitiva através de um teste de controle inibitório. Nossa hipótese foi que indivíduos perdedores apresentam um melhor controle inibitório, uma vez que estariam com um padrão comportamental mais voltado à inibição. Para isso, utilizamos 95 machos revertidos de tilápias-do-nilo (Oreochromis niloticus) que classificados em cinco grupos experimentais independentes, após serem pareados com oponentes: 1. os que vencerem duas lutas seguidas (N=19); 2. os que perderem duas (N=19); 3. os que ganharam a primeira luta e perderem a segunda (N=19); 4. os que perderam a primeira luta e ganharam a segunda (N=19); 5. os que empataram (N=19). Os peixes foram então submetidos ao teste do desvio (detour reaching task), que consiste em treinar os peixes a buscar alimento atrás de uma barreira opaca e, em seguida, testá-los com uma barreira transparente. Espera-se que o peixe evite atravessar diretamente pela barreira transparente para conseguir a recompensa, desviando da mesma a partir da lembrança do desvio na barreira opaca, demostrando um controle inibitório. Foram quantificadas as seguintes variáveis: latência para realizar o desvio, para se alimentar, tempo gasto em frente a barreira na zona incorreta, número de batidas na barreira e o sucesso em realizar o desvio sem bater na barreira transparente. Os dados foram comparados por Generalized Linear Mixed Model (GLMM). A maioria dos animais (94%), apresentaram sucesso na fase de treino com a barreira opaca e passaram pra fase teste, sendo que todos os grupos demonstraram melhora em todas as variáveis da etapa teste, com exceção do sucesso. No geral, o tempo para realizar o desvio e o número de erros diminuiu, demonstrando aprendizagem em relação ao controle inibitório. No entanto, não foram encontradas diferenças significativas entre os tratamentos, indicando que vencedores e perdedores apresentam níveis semelhantes de flexibilidade cognitiva. Tal flexibilidade não está associada ao efeito vencedor/perdedor, mas provavelmente é uma característica chave na tomada de decisões que, assim como em mamíferos, promove o ajuste ao ambiente social em peixes.
Intraspecific fights to define and maintain hierarchy in social animals can be very costly to competitors. Therefore, some behavioral strategies that reduce these costs have been selected. One is the historic of fights, whose individuals with winning experience have a greater chance of fighting and winning, while losing individuals are prone to avoid or lose subsequent fights (winner/loser effect). This requires a certain cognitive ability that allows the individual to interpret and make decisions in the social environment, adjusting their responses according to past experiences (cognitive flexibility). In the present study we tested the relationship between the winner/loser effect and cognitive flexibility through an inhibitory control test. Our hypothesis was that loser individuals have better inhibitory control, since they would have a behavioral pattern more focused on inhibition. For this, we used 95 reversed Nile tilapia males (Oreochromis niloticus) that were classified into five independent experimental groups after being paired with opponents: 1. the ones that won two fights (N=19); 2. the ones that lost two (N=19); 3. the ones that won the first fight and lost the second (N=19); 4. the ones that lost the first fight and won the second (N=19); 5. the ones that tied (N=19). The fish were then submitted to the detour reaching task, which consists of training the fish to seek food behind an opaque barrier and then test them with a transparent barrier. It is expected that the fish avoid crossing directly through the transparent barrier to obtain the reward, detouring from it from the memory of the detour in the opaque barrier, proving an inhibiting control. The following variables were quantified: latency to perform the detour, latency to feed, time spent in front of the barrier in the incorrect zone, number of hits on the barrier and success to perform the detour without hitting the transparent barrier. The data were compared by Generalized Linear Mixed Model (GLMM). Most animals (94%) were successful in the training phase with the opaque barrier and passed the test phase, and all groups showed improvement in all variables of the test stage, except for success. In general, the time to perform the deviation and the number of errors decreased, demonstrating learning in relation to the inhibition control. However, no significant differences were found between treatments, indicating that winners and losers have similar levels of cognitive flexibility. Such flexibility is not associated with the winning/losing effect, but is probably a key feature in decision-making that, as in mammals, promotes adjustment to the social environment in fish.
Intraspecific fights to define and maintain hierarchy in social animals can be very costly to competitors. Therefore, some behavioral strategies that reduce these costs have been selected. One is the historic of fights, whose individuals with winning experience have a greater chance of fighting and winning, while losing individuals are prone to avoid or lose subsequent fights (winner/loser effect). This requires a certain cognitive ability that allows the individual to interpret and make decisions in the social environment, adjusting their responses according to past experiences (cognitive flexibility). In the present study we tested the relationship between the winner/loser effect and cognitive flexibility through an inhibitory control test. Our hypothesis was that loser individuals have better inhibitory control, since they would have a behavioral pattern more focused on inhibition. For this, we used 95 reversed Nile tilapia males (Oreochromis niloticus) that were classified into five independent experimental groups after being paired with opponents: 1. the ones that won two fights (N=19); 2. the ones that lost two (N=19); 3. the ones that won the first fight and lost the second (N=19); 4. the ones that lost the first fight and won the second (N=19); 5. the ones that tied (N=19). The fish were then submitted to the detour reaching task, which consists of training the fish to seek food behind an opaque barrier and then test them with a transparent barrier. It is expected that the fish avoid crossing directly through the transparent barrier to obtain the reward, detouring from it from the memory of the detour in the opaque barrier, proving an inhibiting control. The following variables were quantified: latency to perform the detour, latency to feed, time spent in front of the barrier in the incorrect zone, number of hits on the barrier and success to perform the detour without hitting the transparent barrier. The data were compared by Generalized Linear Mixed Model (GLMM). Most animals (94%) were successful in the training phase with the opaque barrier and passed the test phase, and all groups showed improvement in all variables of the test stage, except for success. In general, the time to perform the deviation and the number of errors decreased, demonstrating learning in relation to the inhibition control. However, no significant differences were found between treatments, indicating that winners and losers have similar levels of cognitive flexibility. Such flexibility is not associated with the winning/losing effect, but is probably a key feature in decision-making that, as in mammals, promotes adjustment to the social environment in fish.
Descrição
Palavras-chave
Controle inibitório, Efeito vencedor/perdedor, Paradigma do desvio, Comportamento social, Inhibitory control, Winning/losing effect, Detour paradigm, Social behaviour