Hormones reflect the impacts of reproductive rest on subsequent pregnancy in a marine predator
Notice bibliographique
Résumé
Abstract After reaching sexual maturity, iteroparous female vertebrates may intermittently skip producing offspring, effectively taking a year of reproductive rest. This may confer benefits to lifetime fitness by enhancing future reproductive success. To identify links between reproductive rest and subsequent reproductive outcomes, the physiological status of female Weddell seals ( Leptonychotes weddellii ) that skipped pupping in the current year (skip females, n = 45) and seals that gave birth (postpartum females, n = 87) was compared. Serum concentrations of hormones (progesterone, oestrogen, luteinizing hormone, follicle‐stimulating hormone, prolactin, thyroxine [T 4 ] and cortisol) were measured during the pupping period, breeding period and early gestation. Transrectal ultrasonography was used to image ovaries and detect early pregnancies. Range‐wide censuses conducted the next year determined if females successfully gave birth. Skip females ovulated up to 4 weeks earlier than postpartum seals and gave birth earlier the following year. Postpartum seals that gave birth late in the pupping season ovulated at fewer days postpartum than seals that gave birth early and had the lowest rates of pregnancy and successful birth. Late‐birthing females were therefore most likely to skip reproduction the following year, likely shifting subsequent reproductive timing forward. Skip females had higher serum concentrations of T 4 , oestrogen and progesterone than postpartum females in both breeding and early gestation periods, plus lower serum cortisol concentrations during early gestation. Serum T 4 concentrations were positively correlated with higher likelihoods that seals were pregnant and would successfully give birth. Postpartum females had higher serum prolactin concentrations than skip females in the pupping and breeding periods. However, prolactin declined across the summer in all animals, likely reflecting a seasonal transition from a breeding to a non‐breeding physiological state. This study revealed that physiological differences between skip and postpartum female Weddell seals persisted long after pupping and into the next reproductive cycle. Findings on trade‐offs between current and future reproduction in a polar pinniped suggest that reproductive rest allows birth timing to advance the next season, helping improve reproductive fitness and maintaining a tight temporal window for birth in the Antarctic marine environment. Read the free Plain Language Summary for this article on the Journal blog.
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Comment cette classification a été obtenuedéplier
Prédiction distillée sur la base complète
Imitation des enseignantsNi prévalence calibrée, ni vérité terrain. Validation humaine à venir. Apprise à partir de 10 348 étiquettes directes de Codex et de 10 348 étiquettes directes de Gemma. Le mode candidate est l'union des têtes enseignantes seuillées; le consensus est leur intersection. Ces sorties portent le statut machine_predicted_unvalidated et ne sont ni des étiquettes humaines ni des étiquettes directes de modèles de pointe.
Scores Codex et Gemma par catégorie
| Catégorie | Codex | Gemma |
|---|---|---|
| Métarecherche | 0,000 | 0,000 |
| Méta-épidémiologie (sens strict) | 0,000 | 0,000 |
| Méta-épidémiologie (sens large) | 0,000 | 0,000 |
| Bibliométrie | 0,000 | 0,000 |
| Études des sciences et des technologies | 0,000 | 0,000 |
| Communication savante | 0,000 | 0,000 |
| Science ouverte | 0,000 | 0,000 |
| Intégrité de la recherche | 0,000 | 0,000 |
| Charge utile insuffisante (le modèle a refusé de juger) | 0,002 | 0,000 |
Scores machine (provisoires)
Les deux têtes enseignantes du modèle étudiant, lues sur ce travail. Un score ordonne la base pour la relecture; il n'affirme jamais une catégorie, et le statut de validation accompagne chaque rangée tel quel.
Scores de référence d'un modèle non mature (critères de maturité non atteints, 7 itérations). Un score ordonne; il n'affirme jamais une catégorie.
score_only:v0-immature-baseline · tel quel depuis la passe de notation : score_only signifie que le nombre peut ordonner les travaux, et qu'aucune étiquette de catégorie n'en découleClassification
machine, non validéePrédiction automatique; un appel candidat d’une seule tête enseignante, pas un consensus.
Le détail, modèle par modèle et score par score, se trouve en fin de page sous « Comment cette classification a été obtenue ».