Defensive mutualisms affect plant and ant island biogeography at a global scale
Bibliographic record
Abstract
Aim: Mutualism can shape biogeographic patterns at macroecological scales. Recently, Delavaux et al. (2024) found that plant mutualisms with mycorrhizae, nitrogen-fixing bacteria, and animal pollinators limit island colonization, weakening the latitudinal diversity gradient (LDG) on oceanic islands. Here, we revisit their analysis and examine whether ants and plants engaged in a common defensive mutualism mediated by extrafloral nectaries (EFN) are similarly under-represented on oceanic islands, and whether this defensive ant-plant mutualism also weakens the LDG on islands. Location: Global. Time period: Present-day species distributions and traits. Major taxa studied: Vascular plants and ants. Methods: We used global trait and occurrence databases to compare ant and plant species richness between oceanic islands and their likely source mainlands for taxa that do and do not interact mutualistically via EFNs. When analyzing the factors that determine whether a plant species occurs on oceanic islands, we also included the mutualism types studied by Delavaux et al. (2024), namely biotic pollination, mycorrhizal fungi, and nitrogen-fixing bacteria, and added plant habit, life history, and phylogeny as covariates. Results: Both plants with EFNs and EFN-visiting ants are significantly over-represented on islands. The species richness of EFN-visiting ants and EFN-bearing plants also positively covary across islands. In ants, engaging in mutualisms mediated by EFNs significantly strengthens, rather than weakens, the LDG on islands, while for plants, EFNs have no effect or strengthen the LDG on islands, depending on data filtering. After accounting for plant habit, life history, and phylogeny, only biotic pollination significantly limits plant colonization of islands, whereas mycorrhizae and nitrogen-fixing bacteria now have positive or non-significant effects, respectively, on island colonization. Main conclusions: EFNs facilitate rather than limit plant and ant colonization on islands. Mutualism does not ubiquitously limit island colonization, and some mutualism types strengthen rather than dampen the LDG on islands.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.000 | 0.001 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".