COUNTERGRADIENT VARIATION IN THE SEXUAL COLORATION OF GUPPIES (POECILIA RETICULATA): DROSOPTERIN SYNTHESIS BALANCES CAROTENOID AVAILABILITY
Bibliographic record
Abstract
Trinidad guppies (Poecilia reticulata) are distributed along an environmental gradient in carotenoid availability that limits the carotenoid content of the orange spots of males. The amount of synthetic red pteridines (drosopterins) in the orange spots covaries with the carotenoid content, such that the ratio of the two types of pigments is roughly conserved across streams. Carotenoids and drosopterins have different spectral properties and thus the ratio of the two types of pigments affects the shape of the orange spot reflectance spectrum. Geographic conservation of the carotenoid:drosopterin ratio suggests that males may be under selection to maintain a particular hue. We tested this hypothesis by comparing the pigmentation and coloration of guppies from six streams in the field to that of second-generation descendants of the same populations raised on three dietary carotenoid levels in the laboratory. The results show clearly that the geographic variation in drosopterin production is largely genetic and that the hue of the orange spots is conserved among populations in the field, relative to the laboratory diet groups. This is a countergradient pattern because genetic differences between populations in drosopterin production mask the effect of carotenoid availability on the hue of the orange spots. The potential for countergradient sexual selection to contribute to reproductive isolation between populations is discussed.
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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) | 0.000 | 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".