Deriving a neutral model of species abundance from fundamental mechanisms of population dynamics
Bibliographic record
Abstract
Summary Ecologists have long sought to derive assembly rules of ecological communities from the fundamental processes of population dynamics, but this goal has remained elusive. Neutral theory has reinvigorated the search by showing that patterns of relative species abundance closely resembling those actually observed arise under the assumption that, to a first approximation, all species are demographically identical on a per capita basis. Here a neutral model is proposed to incorporate all four fundamental processes of population dynamics: birth, death, immigration and emigration. This symmetric model demonstrates that patterns of relative species abundance are fully derivable from these basic processes of population dynamics. The theory derived extends the concept of community by showing that a continuum exists between large‐scale (‘metacommunity’) and small‐scale (‘local community’) processes, eliminating the artificial distinction between the two made by the current neutral theory and by the theory of island biogeography. The population‐based species‐abundance model describes very well the observed patterns of relative species abundance of tropical trees, breeding birds in the USA, aphids at Rothamsted, UK, and estuarine fishes in the north‐east USA. The study also notes that while species assemblages may be well described by the neutral processes of population dynamics, the inference of mechanisms from pattern fitting is not warranted because one‐to‐one relationships between generating mechanisms and community patterns usually do not exist, either in the neutral realm or in the niche world.
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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 | 0.002 | 0.004 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.001 |
| Bibliometrics | 0.001 | 0.000 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.002 | 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".