Social fish have larger brains and greater relative telencephalon sizes: support for the social brain hypothesis from wild, intraspecific comparisons

The Social Brain Hypothesis posits that complex social environments drive
the evolution of larger brains and the enlargement of specific brain
regions. Among species comparisons often report contrasting relationships
between social complexity and brain size, potentially due to confounding
effects of phylogeny, morphology, and ecology. Here, we explore this
relationship in a single fish species, combining behavioural observations
and brain measurements of two wild populations of the cichlid
Neolamprologus brevis, which occupy similar ecological niches across its
range but inhabit contrasting social environments depending on local
shelter abundance. This dataset contains behavioural and neuroanatomical
measurements from two wild populations of the shell-dwelling cichlid
Neolamprologus brevis used to test the social brain hypothesis. The data
include total brain volume, volumes of five brain regions (telencephalon,
optic tectum, cerebellum, medulla, and hypothalamus), body weight, sex,
and population identity for 43 individuals. Neighbour density and
behaviour frequency summaries are included. The dataset also contains R
code used for all statistical analyses and figure generation. Data can be
reused for comparative neuroanatomy, behavioural ecology, and allometric
scaling analyses. No ethical or legal restrictions apply.