RESISTANCE OF THE PREY-TO-PREDATOR RATIO TO ENVIRONMENTAL GRADIENTS AND TO BIOMANIPULATIONS
Bibliographic record
Abstract
Species and their abundances change along environmental gradients, and populations of some species are decimated by introductions of foreign species. We show that the prey-to-predator species ratio is resistant to change. We determined that ratios were about 3:1 for 50 lakes with diversity ranging from 5 to 58 taxa, and with a total combined fauna of 140 insects, crustaceans, and fish. The prey-to-predator ratio range (1.25:1 to 5.20:1) was only 9% of the potential range. Ratios were not related to chemical, thermal, or physical characteristics of lakes. Ratios were generally the same for fishless lakes, for lakes with one or two introduced predators (salmonids), and for lakes with more complex communities with up to 14 predators including five fish species. For the simplest model, this suggests that when a fish species is introduced and becomes established in a lake there is a fundamental ecological compensatory adjustment with either a three species increase in the diversity of prey or the loss of a predator (but no change in diversity). However, we show more complex prey–predator ratio changes occur because certain keystone species regulated community structure and prey diversity. When the keystone fish (a predatory salmonid) was removed from five lakes, the penultimate littoral predator (lake chub) occupied both the pelagic and littoral zones. Consequently, amphipod density decreased, chironomid density increased, and total zooplankton and benthic diversity increased by 31% or 7.8 taxa per lake on average. The mean prey–predator ratio for these five lakes increased significantly from 2.32:1 to 4.16:1. These community based prey–predator ratios were established by single keystone species from their influence on prey, other predators, and community structure.
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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 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.003 | 0.001 |
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; both teacher heads agree on what is shown here.
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".