Evolutionary trends in encephalic morphology among Geophagini cichlid fish: phylogenetic insights and associations with ecological and behavioral traits

The gross encephalic morphology of representatives from 17 genera within the Geophagini tribe is comprehensively characterized, compared, and analyzed into a previously proposed phylogenetic hypothesis. Our morphological investigation highlights the prominence of the visual center within the cichlid encephalon. Notably, constrained phylogenetic analysis reveals probable convergent adaptations in two genera, Cichla and Saxatilia, characterized by diminutive gustatory lobes. In contrast, Retroculus, known for its sediment-shifting habits among Geophagini species, exhibits well-developed gustatory lobes. Previous research has established that species engaging in sediment sifting exhibit modifications in their pharyngeal apparatus and frequently adopt benthivorous feeding strategies, features that appear to be orchestrated by the gustative center in the encephalon. Furthermore, our findings underscore a putative relationship between encephalon morphology and factors such as feeding behavior, environmental conditions (including turbidity and depth), and their association with the studied cichlid species. The neuroanatomical characters proposed in this study hold promise as valuable phylogenetic markers for future analyses and contribute to our understanding of the complex interplay between neuroanatomy, behavior, and ecology within this diverse group of cichlids.