Social fish have larger brains and greater relative telencephalon sizes: support for the social brain hypothesis from wild, intraspecific comparisons
Data files
Sep 10, 2025 version files 44.91 KB
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analysis_script.R
34.99 KB
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brevisBehaviourData.csv
1.93 KB
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brevisBrainData.csv
4.25 KB
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README.md
3.74 KB
Abstract
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.
Dataset DOI: 10.5061/dryad.pk0p2nh2d
Description of the data and file structure
This dataset was collected to examine the relationship between social environment and brain morphology in the shell-dwelling cichlid Neolamprologus brevis. It includes measurements of total brain volume and five major brain regions, as well as individual-level data on body weight, sex, population, and local neighbour density. The dataset supports a study testing the Social Brain Hypothesis using intraspecific comparisons in a wild fish system.
Files and variables
File: brevisBehaviourData.csv
Description: Data of behavioural observations for each focal fish, including frequency of behaviours and neighbour density.
Variables
- observationID: Unique identifier for each individual fish
- behavioralCategory: Categorized behaviour type (e.g., social interaction, aggression, etc.)
- population: Population identity (
chezi= –social,chekonde= +social) - count: Number of observed behaviours in the given category
- total_time: Total time of the observation window (seconds)
- intermediateNeighbour: Number of conspecifics within a 50 cm radius around the focal fish
File: brevisBrainData.csv
Description:
Variables
- id: Unique identifier for each individual fish
- population: Population identity (
chezi= –social,chekonde= +social) - bodyW: Body weight (g)
- standL: Standard body length (cm)
- sex: Sex of the individual (
male,female) - telV: Telencephalon volume (mm3)
- optV: Optic tectum volume (mm3)
- cerV: Cerebellum volume (mm3)
- medV: Medulla volume (mm3)
- hypV: Hypothalamus volume (mm3)
- totalV: Total brain volume (mm3)
File: analysis_script.R
Description: R script used for all statistical analysis and figure generation in the associated manuscript. Includes linear models, regression plots, and summary statistics for brain volume, brain regions, and behavioural comparisons.
Missing values are indicated by NA.
Code/software
The dataset can be viewed and analyzed using R (version 4.3.0 or later), which is free and open-source statistical software available at https://www.r-project.org/.
The analysis script (analysis_script.R) includes the full workflow used to generate the results and figures presented in the associated publication. The script performs the following:
- Loads raw behavioural and brain morphology datasets
- Runs linear models for total brain volume and brain region volumes
- Performs Wilcoxon tests and model-based comparisons for neighbour density
- Generates all plots (Figures 2–4 and supplementary figures) using
ggplot2
The following R packages were used in the analysis:
ggplot2(v3.4.0) – for data visualizationlme4(v1.1-33) – for linear modelsemmeans(v1.8.5) – for estimated marginal meansperformance(v0.10.2) – for model diagnosticsggpubr(v0.6.0) – for figure arrangementgtsummary(v1.7.1) – for reporting tablesggpredictfromggeffects(v1.2.1) – for marginal effects plotting
The script assumes the data files (brevisBrainData.csv, brevisBehaviourData.csv) are located in the same working directory as the R script.
Access information
Other publicly accessible locations of the data:
- This dataset is not hosted elsewhere. It is only available via Dryad.
Data was derived from the following sources:
- All data were collected by the authors as part of the study. No external datasets were used.