EGG COMPOSITION IN RELATION TO FEMALE AGE AND RELAYING: CONSTRAINTS ON EGG PRODUCTION IN THICK-BILLED MURRES (URIA LOMVIA)
Bibliographic record
Abstract
Abstract There is growing awareness that costs associated with egg production play a significant role in shaping avian life histories. The life-history strategy of the Thick-billed Murre (Uria lomvia), a colonial, cliff-breeding seabird of Arctic waters, is characterized by a high annual adult survival rate, deferred breeding, and laying of a single-egg clutch. The single-egg clutch is a widespread phenomenon among seabirds and is generally thought to reflect demands of chick provisioning, rather than egg production. We compared composition of eggs laid by Thick-billed Murres most likely to be physiologically constrained in their capacity to produce eggs (young females with no prior experience, and females forming replacement eggs) to that of first eggs laid by early laying females (typically older, more experienced members of the population). Young, inexperienced females laid 4–18 days past the populationwide median laying date, and their eggs averaged 13% lighter in mass than those laid by early layers. Compared to early laid eggs, shell mass on young females’ eggs was similar to that predicted from egg mass, but their eggs had a lower yolk-to-albumen ratio. There was little difference between the two groups in relative protein content of albumen, relative protein or lipid content of yolk, or amino acid makeup of protein in yolk or albumen. Replacement eggs averaged 6% lighter in mass than first eggs laid by the same females earlier that season. As with young females’ eggs, replacement eggs had shells similar in mass to that predicted from egg mass, but lower yolk-to-albumen ratios, when compared to early laid eggs. Both protein and lipid concentrations in yolk were similar in first and replacement eggs, but replacements were deficient in albumen protein. Amino acid makeup of protein in yolk and albumen was similar in the two groups. Those results suggest that any limitations on egg production acting on young, inexperienced females are manifested in delayed laying and reductions in overall egg mass and proportional yolk content, but not in variation in biochemical composition of their eggs. Limitations on females forming replacement eggs are manifested not only in reduced egg mass and yolk content (as with young females), but also in changes in the biochemical composition of eggs; in particular, evidence suggests that relaying females may face a deficit of endogenous protein. The existence of such limitations suggests that demands of egg production can be significant even in a species that lays a single-egg clutch.
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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".