Relative importance of endogenous and exogenous mechanisms in maintaining phytoplankton species diversity
Bibliographic record
Abstract
The competitive exclusion principle poses the pressing question of how biodiversity is maintained in nature. Many mechanisms have been proposed to explain diversity and to resolve what has become known as the “paradox of the plankton”. We propose a dichotomy among these mechanisms in order to enable empiricists to begin testing their relative importance. Specifically, the mechanisms can be categorized as being internally generated or as depending on forces external to the competitive community. Here we tested whether the internal competitive dynamics of a phytoplankton assemblage or externally generated resource variability (a disturbance) were more effective at maintaining species diversity over time. We also tested whether the species composition of assemblages was important in determining the persistence of species diversity. We employed controlled microcosm experiments in which we either imposed exogenous variability in nutrient availability via serial dilution or allowed the communities to remain completely undisturbed. We found that species diversity was maintained most effectively in undisturbed microcosms in which only internal dynamics regulated coexistence. We also found that the community composition of the assemblage significantly interacted with the disturbance regime in determining species diversity. This confirmed the importance of internal dynamics and community composition in maintaining species diversity.
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 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 | 0.003 |
| 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 | 0.002 |
| Scholarly communication | 0.002 | 0.001 |
| Open science | 0.001 | 0.001 |
| 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 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".