Speciation in sympatric sticklebacks: hybridization, reproductive isolation and the maintenance of diversity
Notice bibliographique
Résumé
This research examined genetic, morphological, ecological and behavioral mechanisms maintaining divergence between a pair of sympatric stickleback species (Gasterosteus aculeatus complex) from Paxton Lake, British Columbia, Canada. When raised in the lab, F₁ hybrids showed no evidence of inferiority relative to parental species for the following characters: fertilization success, hatch success, growth rate, fecundity, fluctuating asymmetry, and parental care. Although these are common postmating isolation mechanisms between many other species, if they operate in the wild in this system their effects are likely small and of little biological importance. When raised in the wild, in either of two main habitats, F₁ hybrids suffered a significant reduction in growth rate relative to parental species. Hybrid disadvantage resulted from morphological intermediacy which affected resource exploitation efficiency. Hybrid disadvantage is thus a function of the ecological environment, rather than developmental inviability or physiological inferiority. This ecological disadvantage provides the strongest postmating barrier known between these species. Though this is one of the first demonstrations that niche-based selection pressures are a dominant mechanism of postmating isolation, I argue that this may be common in the early stages of speciation. Since gene flow between species must occur through reproductively fit F₁ hybrids, I asked whether male F₁ hybrids are sexually selected against by females of the parental species. I provide experimental evidence that mate choice by females of the parental species must be coupled with habitat preference for there to be sexual selection against hybrids. I measured the degree of genetic divergence between the species in four morphological characters and one fitness component by rearing six lines (parentals and first and second generation hybrids; 109 families total) in the lab. Joint-scaling tests on phenotype means and variances suggest that epistasis contributes significantly to genetic divergence of parental lines for two of the characters, gill raker length and growth rate. Dominance effects contribute significantly to divergence in plate number and pelvic spine length. A simple additive model was sufficient for only gill raker number. A biometrical approach to gene number estimation suggested that character differences are coded for by 1 to 60 genes, depending on the trait. The tremendous discrepancy in these estimates may reflect real differences among characters in genetic divergence, but the estimates are likely unreliable due to the rejection of several important assumptions of the method. My findings are compared to other recent estimates of genetic divergence in natural populations, and discussed in the context of speciation in sticklebacks.
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 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) | 0,000 | 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 ».