Biotic interchange has structured Western Hemisphere mammal communities
Bibliographic record
Abstract
Abstract Aim Many hypotheses posit that species‐rich tropical communities are dominated by species–species interactions, apparent as competitive exclusion or character displacement, whereas species‐poor temperate communities are dominated by species–environment interactions. Recent studies demonstrate a strong influence of macroevolutionary and biogeographical factors. We simultaneously test for the effects of species interactions, climate and biotic interchange on Western Hemisphere mammal communities using a phylogenetic and functional diversity approach. Location Western Hemisphere. Time period Modern. Major taxa studied Mammalia. Methods Using Western Hemisphere mammal distributional and body mass data, we calculate body mass dispersion, phylogenetic diversity (Net Relatedness Index) and assemblage‐averaged rates of co‐occurrence (Checkerboard scores) in 100 km × 100 km grid cells under an equal area projection. We model body mass dispersion as a function of phylogenetic diversity, co‐occurrence rates and species richness, as well as mean annual temperature and precipitation. We infer rates of dispersal among the temperate and tropical zones of the Western Hemisphere using phylogenetic methods. Results The dispersion of northern temperate mammal body masses is higher than null communities and shows correlated change with climate, consistent with resource competition and environmental filtering. Conversely, the dispersions of tropical and southern temperate mammal body masses are lower than and not differentiable from null expectations, respectively, suggesting a limited role of species–species and species–environment interactions at the grain of our analysis. Low tropical body mass dispersion and phylogenetic evenness are best explained by the high rates of faunal mixing. High rates of dispersal might also explain the similarity in community structure between the southern temperate and tropical zones. Main conclusions Mammal community assembly processes differ among the temperate and tropical zones of the Western Hemisphere, and faunal mixture during dispersal events, such as the Great American Biotic Interchange (Pliocene c . 3 Ma), may have been important in structuring Western Hemisphere mammal communities.
Fetched live from OpenAlex and de-inverted. Abstracts are not stored in this database: the inverted indexes are 8.6 GB of the frame’s 9.3 GB of text, and the host has 13 GB free.
How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.001 | 0.002 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| 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 teacher head, 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".