Data and code from: Coexisting ant species differ in ability to meet their intrinsic nutritional needs
Abstract
Coexisting species are often assumed to reduce competition by foraging for different foods with different nutrients. Few studies have examined whether this nutritional partitioning reflects innate differences in nutritional needs. Here, we tested for overlapping estimates of nutritional intake (tissue isotopes: δ15N, elemental ratios: C:N) among 17 co-occurring Australian ant species collected from the field. We then measured the innate nutritional selectivity (protein:carbohydrate intake targets: P:C IT) of these ant species with competition-free lab feeding experiments. By comparing the nutritional ecology of free-ranging and lab-maintained ants, we inferred whether extrinsic factors prevent ant species from foraging nutritionally optimized diets. Analyses of free-ranging ants indicated dietary and nutritional partitioning, with worker δ15N (proxy for realised intake) spanning 7.1 ‰ among species and C:N (proxy for realised intake) varying 1.33-fold. Lab-maintained ants, by contrast, exhibited overlapping P:C ITs (innate selectivity), with a mean of 1.00 (±0.06 SE) and range 0.60–1.42 among species. Lab P:C ITs were not predictive of species-mean δ15N or C:N in the field (H1). This indicates that, despite relatively narrow and overlapping innate macronutrient selectivity, realised field diets diverge widely; pairwise coupling was weak at best (H2; ~5 % variance) and residual/compensatory divergence was unsupported (H3), suggesting nutritional shortfalls under natural constraints (e.g., competitive monopolisation of carbohydrates, brood-mediated demand, risk-sensitive foraging) can decouple innate targets from realised intake. This study illustrates the power and novelty of integrating field-based measures with controlled lab-based experiments to test classic hypotheses in nutritional ecology. Further work will be needed to test whether nutritionally imbalanced diets are physiologically costly for free-ranging ant colonies, and whether population-level costs scale up to impact community-level stability.
This folder contains the data tables, phylogeny, and generated outputs used by riskas-2025-ant-nutritional-needs.Rmd.
Files in This Folder (DATA.zip)
Core Data Tables
Tot_6days.csv
Replicate-level dataset (multiple rows per species; replicate IDs often appended, e.g., _a, _b). Contains raw totals, sham/evaporation corrections, per-worker values, per-day rates, and mass-specific (per mg) rates for total intake and macronutrients.
Means_rhr.csv
Species-level summary table (one row per species). Contains species means/SD/SE across replicate rows from Tot_6days.csv, plus species traits used in models and figures.
Phylogeny
mr_phylo.tre
Tree used for phylogenetic distance (cophenetic) matrices and phylogeny-controlled analyses.
Generated Outputs (Written by the RMarkdown)
Table_S6_species_pairs.csv— Derived table of flagged convergent/divergent species pairs (created by analysis code).Fig_final_mismatch_ranked.png,FigS6_residual_divergence.png— Exported figures created during rendering.riskas-2025-ant-nutritional-needs.html(+*.knit.mdand/or Chrome HTML) — Rendered outputs from the analysis pipeline.
Key Identifiers
Species Naming
SPEC = species identifier using underscores (e.g., Iridomyrmex_splendens)
In Tot_6days.csv, some fields may use a replicate-coded ID (e.g., sp.c) where the replicate letter is appended to species.
Scaling and Naming Conventions
Suffix Conventions (General)
*_PW= per workerd_rate_*= per worker per day (this experiment is a 6-day assay; many rates are totals divided by 6)*_MC= mass-corrected / mass-specific (typically a rate divided by worker massw.mass; i.e., per mg worker mass)
Sham/Evaporation Correction
Many intake totals are recorded both before and after correction for sham/evaporation controls:
*_no_sh= measured without sham correction (raw)*_shd= sham/evaporation/control estimate- Corrected totals are typically represented as
d_*variables (e.g.,d_all_consumed,d_carb,d_prot), where the corrected value is the raw value minus sham.
pw_pc_sh vs pw_pc_nosh (Important)
These two columns represent alternative definitions of the realised protein:carbohydrate (P:C) intake ratio:
pw_pc_sh: P:C calculated including scattered and hoarded diet.pw_pc_nosh: P:C calculated excluding scattered and hoarded diet.
Manuscript results/figures use the version specified in the relevant code blocks (often pw_pc_sh when the intention is to include scattered/hoarded diet in realised intake).
Column Guide
Tot_6days.csv (Replicate-Level)
IDs / Taxonomy
SF,Genus,SPEC(+ replicate-coded ID fields such assp.cif present)
Traits / Covariates (Some May Be Unused in the Paper)
d15N,N,C,CNw.mass,logw.mass- Additional metadata columns may be present but not used in manuscript analyses
Raw Totals (Over the Assay; Before Sham Correction)
total_no_sh,carb_tot_no_sh,prot_tot_no_sh
Raw Totals Per Worker
total_no_sh_PW,carb_tot_no_sh_PW,prot_tot_no_sh_PW
Sham/Evaporation Controls
shd,carb_shd,prot_shd
Corrected Totals
d_all_consumed(total corrected for sham)d_corrected(corrected per worker)d_carb,d_prot(corrected totals for carbs/protein)d_carb_PW,d_prot_PW(corrected per worker)
Per-Day Rates (Per Worker Per Day)
d_rate_tot,d_rate_cho,d_rate_pro- Sometimes also
*_nosh_RATEvariants for rates based on raw totals
Mass-Specific Rates
d_rate_tot_MC,d_rate_cho_MC,d_rate_pro_MC(rate divided byw.mass)
Realised P:C Ratio
pw_pc(replicate-level realised P:C ratio)
Means_rhr.csv (Species-Level)
IDs / Taxonomy
SF,Genus,SPEC
Traits / Covariates
d15N,w.mass,logw.mass- Additional morphology/metadata columns may be present (not necessarily used in manuscript analyses)
Species-Level Intake Summaries
Most replicate-level variables from Tot_6days.csv appear here as species summaries with suffixes:
*_mean= mean across replicates*_sd= standard deviation across replicates*_SE= standard error across replicates
This includes total intake, carbohydrate intake, protein intake, sham controls, corrected totals, per-day rates, and mass-specific rates (as available in the table).
Species-Level Realised P:C Ratio (Two Definitions)
pw_pc_sh/pw_pc_sh_SE= realised P:C ratio including scattered/hoarded diet (and its SE)pw_pc_nosh= realised P:C ratio excluding scattered/hoarded diet
Columns Not Used in the Paper
Some columns appear in the raw/summarised tables but are not used in the manuscript analyses and can be ignored for reproducing the reported results/figures. Examples include (non-exhaustive):
LP.colonysize, C.colonysize, col.size, HL, HW, hl.hw, activity.time, and other auxiliary metadata fields.
Reproducibility Notes
- The analysis is executed via
riskas-2025-ant-nutritional-needs.Rmd. - Outputs in this folder (figures/tables/html) are generated during rendering; delete and re-knit to regenerate cleanly.
- Keep filenames and relative paths stable to avoid breaking the RMarkdown pipeline.