Sex allocation and parental quality in tree swallows
Bibliographic record
Abstract
In species with extrapair mating, females may choose a social mate who will contribute to the successful raising of their brood and a sire who can enhance the genetic quality of offspring. Female choice of social mate and genetic sire may thus be independent events, directed toward different types of reproductive benefits. Furthermore, if reproductive benefits derived through mating preferences differ for sons and daughters, a coupling between sex ratio adjustment and mate choice would be favored by selection. In this paper, we examined whether females adjust the primary sex ratio of offspring to the quality of the social male and/or the extrapair sire in a socially monogamous species with frequent extrapair mating, the tree swallow Tachycineta bicolor. Recent evidence suggests that females obtain compatible genes’ benefits through extrapair mating in this species. If genetic quality is more important for male than female fitness and contributes to higher variance in reproductive success among males than females, sex allocation theory would predict a male-biased sex ratio among extrapair offspring. However, we found no indication of sex ratio bias with paternity in mixed paternity broods. Instead, females skewed the sex ratio toward males in broods without extrapair paternity, which probably reflects a higher phenotypic quality of these males. Furthermore, we confirmed earlier findings that females in good condition produce male-biased broods. Thus, our results indicate that female tree swallows adjust the primary sex ratio to the phenotypic quality of their social mate and themselves and not to the genetic sire of their offspring.
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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".