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- Adult neurogenesis in the brain of the Mozambique tilapia, Oreochromis mossambicusPublication . Teles, Magda C; Sîrbulescu, Ruxandra F.; Wellbrock, Ursula M.; Oliveira, Rui Filipe; Zupanc, Günther K. H.Although the generation of new neurons in the adult nervous system ('adult neurogenesis') has been studied intensively in recent years, little is known about this phenomenon in non-mammalian vertebrates. Here, we examined the generation, migration, and differentiation of new neurons and glial cells in the Mozambique tilapia (Oreochromis mossambicus), a representative of one of the largest vertebrate taxonomic orders, the perciform fish. The vast majority of new cells in the brain are born in specific proliferation zones of the olfactory bulb; the dorsal and ventral telencephalon; the periventricular nucleus of the posterior tuberculum, optic tectum, and nucleus recessi lateralis of the diencephalon; and the valvula cerebelli, corpus cerebelli, and lobus caudalis of the cerebellum. As shown in the olfactory bulb and the lateral part of the valvula cerebelli, some of the young cells migrate from their site of origin to specific target areas. Labeling of mitotic cells with the thymidine analog 5-bromo-2'-deoxyuridine, combined with immunostaining against the neuron-specific marker protein Hu or against the astroglial marker glial fibrillary acidic protein demonstrated differentiation of the adult-born cells into both neurons and glia. Taken together, the present investigation supports the hypothesis that adult neurogenesis is an evolutionarily conserved vertebrate trait.
- The correlated evolution of social competence and social cognitionPublication . Varela, Susana A. M.; Teles, Magda C; Oliveira, Rui Filipe1. Knowing which of correlated traits are more strongly targeted by selection is crucial to understand the evolutionary process. For example, it could help in understanding how behavioural and cognitive adaptations to social living have evolved. 2. Social competence is the ability of animals to optimize their social behaviours according to the demands of their social environment. It is a behavioural performance trait that expresses how well a whole organism performs complex social tasks, such as choosing mates, raising offspring, participating in dominance hierarchies, solving conflicts or forming social bonds. Non‐social competence, on the other hand, is the ability of animals to optimize their non‐social behaviours according to the demands of their non‐social environment, such as finding food or avoiding predators. 3. Social and non‐social cognition are correlated lower‐level traits of social and nonsocial competence, respectively, encompassing the underlying psychological and neural mechanisms of behaviour that allow animals to acquire, encode, store and recall information about their social and non‐social environments. 4. Here, we employ the theoretical framework that selection acts on performance traits first and on lower‐level traits only secondarily, to propose a new approach to the study of the evolution of social cognition. 5. We hypothesize that when selection favours social competence, the cognitive system becomes more adapted to the social domain, making species biased for social information, and increasing their degree of sociality. The opposite can happen when selection favours non‐social competence. 6. The level of specialization that the cognitive system can attain depends on whether social and non‐social competence are correlated with the same cognitive lower‐level traits. This in turn will determine whether species will evolve a type of social cognition that is general—that contributes with cognitive abilities that can be used in both social and non‐social environments—or modular—that contributes with cognitive abilities that are specific to the social environment.