Individual repeatability in laying behaviour does not support the migratory carry‐over effect hypothesis of egg‐size dimorphism in <i>Eudyptes penguins</i>
Bibliographic record
Abstract
Penguins of the genus Eudyptes are unique among birds in that their first‐laid A‐egg is 54–85% the mass of their second‐laid B‐egg. Although the degree of intra‐clutch egg‐size dimorphism varies greatly among the seven species of the genus, obligate brood reduction is typical of each, with most fledged chicks resulting from the larger B‐egg. Many authors have speculated upon why Eudyptes penguins have evolved and maintained a highly dimorphic 2‐egg clutch, and why it is the first‐laid egg that is so much smaller than the second, but only recently has a testable, proximate mechanism been proposed. In most species of Eudyptes penguins females appear to initiate egg‐formation at sea during return migration to breeding colonies. In macaroni penguins E. chrysolophus , females with a shorter pre‐laying interval ashore (and thus presumably greater overlap between migration and egg‐formation) lay more dimorphic eggs, suggesting a physiological conflict may constrain growth of the earlier‐initiated A‐egg. This migratory carry‐over effect hypothesis (MCEH) was tested in eastern rockhopper penguins E. chrysocome filholi on Campbell Island, New Zealand, by recording the arrival and lay dates, body sizes, and egg masses of transponder‐tagged females over two years. Females with longer pre‐laying intervals laid less dimorphic clutches, as predicted by the MCEH. However, repeated measures of individual females revealed that within‐individual variation in egg‐size dimorphism between years was unrelated to within‐individual variation in pre‐laying interval. Egg masses, and to a lesser extent egg‐size dimorphism, were highly repeatable traits related to body size and body mass. These results and a detailed consideration of the MCEH suggest that egg‐size dimorphism in Eudyptes penguins is unlikely to be caused by a migratory carry‐over effect.
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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 | 0.003 | 0.001 |
| 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 | 0.001 | 0.000 |
| Research integrity | 0.000 | 0.001 |
| 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".