Bluegill Coloration as a Sexual Ornament: Evidence From Ontogeny, Sexual Dichromatism, and Condition Dependence
Bibliographic record
Abstract
Abstract In aquatic environments, visual communication is expected in animals that inhabit clear, shallow waters. Here, we investigate variation in the colorful traits of bluegills, Lepomis macrochirus , to elucidate their possible function. Bluegills use alternative mating tactics whereby males develop into one of two irreversible phenotypes termed parental and cuckolder. Parentals build and defend nests and care for offspring whereas cuckolders obtain matings by sneaking copulations. We hypothesized that bluegill coloration might function as a sexual ornament in parental males and that ornamental coloration might serve as an honest indicator of male quality. We predicted that coloration should be more pronounced in parental males than in females and immature males and should be more pronounced during the breeding season. We also predicted that males in better condition should be more intensely colored than fish in poor condition. To test our predictions, we sampled 510 bluegills during the breeding and post‐breeding seasons at nine lakes in southern Ontario, Canada, in 2007. We used reflectance spectrometry to quantify the coloration of five body regions, aged and sexed each fish, and calculated Fulton’s condition factor from morphological measurements. A separate experiment showed that color did not fade several minutes post capture, suggesting that coloration could be measured reliably and consistently. We found that color was influenced by maturity, sex, and season, in the predicted direction, for three body regions (breast, cheek, and opercular flap). We also found that color varied with the condition of males such that males in better condition were darker for the sexually dichromatic ventral and facial regions. Our findings therefore suggest that some colorful traits in bluegills may serve as condition‐dependent sexual signals during the breeding season. Our research contributes to a growing appreciation of the importance of visual signaling in aquatic environments.
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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) | 0.001 | 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 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".