Flexibility in the colouration of the meninx (brain covering) in the guppy (Poecilia reticulata): investigations of potential function
Bibliographic record
Abstract
Many organisms can change the apparent colour of their bodies by altering the aggregation of pigment in chromatophores in a process known as physiological colour change. In this study, we investigate a previously unstudied example of physiological colour change, from clear to black, of a brain covering, or meninx, in the guppy ( Poecilia reticulata Peters, 1859). UV protection in bright light was our primary hypothesis for the function of the meningeal colour, with a cost of increased conspicuousness to avian predators selecting for plasticity in the trait. An alternate hypothesis was that this flexible trait could be a physiological by-product of stress. Thus, we investigated the response of meningeal colour to light, stress, and simulated predator attacks, and also whether the black meninx affected conspicuousness to potential predators. Meningeal response to higher light levels did not differ from baseline responses. However, we did find that stress induced a sex-biased, rapid darkening of the meninx; this darkening then declined over time. These results suggest that meningeal blackness could be used as a novel, noninvasive indicator of stress level in guppies. We found no evidence for a role of predation in meningeal colour: meninx colour did not respond to the presence of a predator model and human “predators” detected similar numbers of guppies with black meninges and guppies with clear meninges.
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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 | 0.000 | 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) | 0.001 | 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 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".