Effect of a Territorial Challenge on the Steroid Profile of a Juvenile Songbird
Bibliographic record
Abstract
Aggression is a social behavior that is critical for survival and reproduction.In adults, circulating gonadal hormones, such as androgens, act on neural circuits to modulate aggressive interactions, especially in reproductive contexts.In many species, individuals also demonstrate aggression before reaching gonadal maturation.Adult male song sparrows, Melospiza melodia, breed seasonally but maintain territories year-round.Juvenile (hatch-year) males aggressively compete for territory ownership during their first winter when circulating testosterone is low.Here, we characterized the relationship between the steroid milieu and aggressive behavior in free-living juvenile male song sparrows in winter.We investigated the effect of a 10 min simulated territorial intrusion (STI) on behavior and steroid levels in blood, 10 microdissected brain regions, and four peripheral tissues (liver, pectoral muscle, adrenal glands, and testes).Using liquid chromatography-tandem mass spectrometry (LC-MS/MS), we quantified 12 steroids: pregnenolone, progesterone, corticosterone, 11-dehydrocorticosterone, dehydroepiandrosterone, androstenedione, testosterone, 5a-dihydrotestosterone, 17b-estradiol , 17a-estradiol, estrone, and estriol.We found that juvenile males are robustly aggressive, like adult males.An STI increases progesterone and corticosterone levels in blood and brain and increases 11-dehydrocorticosterone levels in blood only.Pregnenolone, androgens, and estrogens are generally non-detectable and are not affected by an STI.In peripheral tissues, steroid concentrations are very high in the adrenals.These data suggest that adrenal steroids, such as progesterone and corticosterone, might promote juvenile aggression and that juvenile and adult songbirds might rely on distinct neuroendocrine mechanisms to support similar aggressive behaviors.
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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 | 0.000 | 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 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".