Eggshell Conspicuousness is Related to Paternal Brood Patch Vascularisation in the American Thrashers
Bibliographic record
Abstract
Conspicuous blue-green egg colouration has been of interest to scientists and naturalists for more than a hundred years; however, the function of this trait has never been fully understood and has spurred extensive debate. The American thrashers exhibit great variation in egg colouration and patterning, and also show variation in male brood patch development. A recent hypothesis suggests that conspicuous egg colouration has evolved as the product of sexual conflict, where females may create conspicuous eggs to obtain greater amounts of male care, either in the form of male incubation or incubation assistance to prevent their eggs from being vulnerable to visually orienting predators and brood parasites. The American thrashers, a genus comprising of 10 species, exhibits striking variation in egg colouration and patterning, and also show variation in male brood patch development. By using avian visual modelling, I show that blue-green chroma of American thrasher eggs is positively related to their degree of conspicuousness against a nest background, while brown chroma is negatively related. Interestingly, the degree of male brood patch vascularisation is directly related to eggshell conspicuousness in American thrashers. I suggest that in the American thrashers, male brood patch vascularisation has evolved in response to conspicuous eggshell colouration to mitigate visual risks. Here I show that the degree of male brood patch vascularisation is directly related to relative paternal incubation effort in more than 300 North American breeding birds. This suggests that American thrasher species that possess both conspicuous eggs and brood patches, have most likely evolved to keep these conspicuous nest contents concealed, thereby reducing risk of visual detection. I suggest that these patterns are not unique to thrashers, but may extend to several avian families.
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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 | 0.001 | 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 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".