Notice bibliographique
Résumé
There is widespread evidence that egg size has evolved through offspring and maternal fitness demands. Larger eggs typically bestow more nutrients, a larger birth weight and increased chance of survival on the offspring. Egg size is balanced with egg number to maximize maternal reproductive success. However, a new player has recently been added to the roster: sperm limitation, which occurs when there is an insufficient quantity of sperm to fertilize all of the available eggs. It has been suggested that in externally fertilizing animals, sperm limitation could also act as a selective force influencing egg size.Externally fertilizing animals, such as a sea urchins or fish, release their sperm and eggs into the surrounding environment with the hope that a sperm will bump into an egg and successfully fertilize it. It has recently been shown in three species of sea urchin that larger eggs need lower sperm concentrations in order to be successfully fertilized. Christopher MacFarlane from the University of East Anglia in the UK along with colleagues from Brandon University and the University of British Columbia in Canada sought to determine whether the same could be said for sockeye salmon, a fish with substantial natural variation in egg size where males and females spawn in much closer association compared with broadcast spawning marine invertebrates like sea urchins.In order to test whether larger sockeye salmon eggs were preferentially fertilized under conditions of sperm limitation, the authors collected sperm from 20 males and pooled eggs from 15 females. Dividing the pooled eggs into groups, the team added just enough sperm to each group of eggs to ensure fertilization success rates ranging from 20% to 80%. After allowing the eggs to incubate for 10 days, they measured the surface area of the fertilized and unfertilized eggs. Finally, the authors also included two treatments where all the eggs or none of the eggs were fertilized to account for possible changes in the size of the egg over the course of time or in response to fertilization. This also allowed the team to test whether there is a relationship between egg size and fertility when a surfeit of sperm is available.The team found that under sperm-limitation conditions, the eggs that were fertilized successfully had a significantly larger surface area (by 7%) than the unfertilized eggs, suggesting that increased egg size could evolve under conditions of sperm limitation.This study by MacFarlane and colleagues demonstrates that in addition to offspring and maternal fitness demands, egg size could also be influenced by sperm limitation in salmon. The next step in this line of research is to assess the importance of sperm limitation in fish in a natural setting. Though salmonids are generally considered to have high fertility in the environment, other species may not be so lucky. One thing seems to emerge clearly from this study: it's easier to hit a bigger target!
Récupéré en direct depuis OpenAlex et désinversé. Les résumés ne sont pas conservés dans cette base de données : les index inversés représentent 8,6 Go des 9,3 Go de texte de la base, et le serveur dispose de 13 Go libres.
Comment cette classification a été obtenuedéplier
Prédiction machine sur la base complète
Imitation des enseignantsNi prévalence calibrée, ni vérité terrain. Validation humaine à venir. Le volet Gemma est une étiquette directe du modèle pour chaque travail de la base, lue sur la notice réduite au titre. Le volet Codex est un classifieur appris des 10 348 étiquettes directes de Codex et calibré sur les taux pondérés de l'échantillon; les champs sans appui suffisant ne portent aucun appel Codex. Le mode candidate est l'union des deux volets; le consensus est leur intersection. Ces sorties portent le statut machine_predicted_unvalidated et ne sont pas des étiquettes humaines.
Scores du classifieur distillé par catégorie (deux têtes)
| Catégorie | Codex | Gemma |
|---|---|---|
| Métarecherche | 0,001 | 0,006 |
| Méta-épidémiologie (sens strict) | 0,001 | 0,001 |
| Méta-épidémiologie (sens large) | 0,001 | 0,001 |
| Bibliométrie | 0,001 | 0,001 |
| Études des sciences et des technologies | 0,002 | 0,001 |
| Communication savante | 0,003 | 0,003 |
| Science ouverte | 0,001 | 0,003 |
| Intégrité de la recherche | 0,002 | 0,001 |
| Charge utile insuffisante (le modèle a refusé de juger) | 0,150 | 0,053 |
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 source (Gemma direct ou Codex distillé), 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 ».