Abstract
Analyses of the macroevolutionary correlates of brain structure volumes allow pinpointing of selective pressures influencing specific structures. Here we use a multiple regression framework, including phylogenetic information, to analyze brain structure evolution in 43 Tanganyikan cichlid species. We analyzed the effect of ecological and sexually selected traits for species averages, the effect of ecological traits for each sex separately and the influence of sexual selection on structure dimorphism. Our results indicate that both ecological and sexually selected traits have influenced brain structure evolution. The patterns observed in males and females generally followed those observed at the species level. Interestingly, our results suggest that strong sexual selection is associated with reduced structure volumes, since all correlations between sexually selected traits and structure volumes were negative and the only statistically significant association between sexual selection and structure dimorphism was also negative. Finally, we previously found that monoparental female care was associated with increased brain size. However, here cerebellum and hypothalamus volumes, after controlling for brain size, associated negatively with female-only care. Thus, in accord with the mosaic model of brain evolution, brain structure volumes may not respond proportionately to changes in brain size. Indeed selection favoring larger brains can simultaneously lead to a reduction in relative structure volumes.
Highlights
There is compelling evidence across very diverse species that both ecological and social factors can play an important role in shaping brain evolution [1,2,3,4]
Cerebellum volume was significantly correlated with sexual selection, depth and habitat (Table 1)
When we tried to tease apart the effect of sexual selection, neither mating competition nor sexual dimorphism was significantly correlated with cerebellum volume on their own (p = 0.10 and p = 0.18, respectively), it appears the effect is mediated by a combination of the sexually selected traits
Summary
There is compelling evidence across very diverse species that both ecological and social factors can play an important role in shaping brain evolution [1,2,3,4]. Social living appears to have played a key role in shaping brain evolution and larger brains have been linked with invasion success and longer lifespan [4,10,11,12,13,14]. Larger brains have been associated with tool use, survival, invasion success and developmental mode [15,16,17]. Less studied than mammals or birds, available evidence in fishes shows an association between ecological niche, parental care (biparental or monoparental care) and brain size [18,19]
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
