Monkeys Swimming Across Rivers Refine Questions About the Riverine Barrier Hypothesis
Bibliographic record
Abstract
The Riverine Barrier Hypothesis posits that species distributions are limited by large rivers acting as geographical barriers. Accordingly, large rivers have long been thought to be a major driver of the extensive speciation and high levels of biodiversity among platyrrhine primates in South and Central America. Direct observations of river crossings provide evidence that complements studies of genetic diversity that can together shed new light on this hypothesis. Here, we discuss recent video evidence of howler monkeys successfully swimming across the Rupununi River in Guyana and the Panama Canal. The footage clearly reveals that howler monkeys can and do cross such bodies of water. These video observations help to refine questions about the species and circumstances under which rivers are barriers to gene flow. We end by joining other scientists who call for increased collaborations with local people living near river crossing sites to improve our knowledge and understanding of the frequency, contexts, and traits of the rivers and animals that characterize river crossings. Local knowledge provides new answers and helps refine questions about the river barrier hypothesis.
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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 | 0.000 | 0.001 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 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".