Genetic relationships among threespine sticklebacks, Gasterosteus aculeatus
Notice bibliographique
Résumé
Threespine sticklebacks (Gasterosteus aculeatus) inhabit both marine and freshwater environments along the Pacific coast of North America, In this study, sticklebacks collected from 73 locations on Vancouver Island, the Sechelt Peninsula and the lower Fraser River Valley of British Columbia, and six sites in northwestern Washington State, were assayed by starch gel electrophoresis in order to examine relationships among and between marine (trachurus) and freshwater (leiurus) populations. Six enzymes, coded for by eight genetic loci, were examined. Of these, two aere monomorphic for the same allele in all populations, the remainder were polymorphic to varying degrees. Laboratory breeding studies employing both marine and freshwater fish as parents confirmed the genetic interpretation of observed variability in isozyme banding patterns. One of the monomorphic enzytaes, isocitrate dehydrogenase, exhibited a sexually dimorphic isozyme pattern. Levels of polymorphism and heterozygosity were slightly higher than average, bat within the range of those characterizing other vertebrate species. In general, genotypic ratios conformed to Hardy-Heinberg expectations, and allele frequencies within populations did not shift over short time periods. Gene frequencies did not vary among sticklebacks of different sizes nor among those caught by different methods from the same population. Gene frequencies at all polymorphic loci were significantly heterogeneous among stickleback populations. Average frequencies at two loci (Pgm and Mdh-3) differed significantly between marine and freshwater fish. In addition, average frequencies at two other loci (Mdh-1 and Ck) were different among sticklebacks inhabiting different types of freshwater environments. Among freshwater populations the Ck ⁸⁵ and Pgm ⁹⁰ alleles displayed clinal geographic variability in frequency, possibly as a result of the differential sampling of various freshwater habitat types in different regions. Allele frequencies at three loci (Pgm, Ck and Pgi-2) differed between marine sticklebacks collected from the Strait of Georgia and those from waters off the vest coast of Vancouver Island. Calculation of Nei’s genetic distance indicated that while marine populations are relatively homogeneous at electrophoretic loci, freshwater populations are highly heterogeneous. The average genetic distance between marine and freshwater populations was similar to that separating pairs of freshwater populations. The genetic distance between freshwater populations was greater between than within watersheds, but allele distributions at individual loci did not differ significantly between two watersheds levels of polymorphism and heterozygosity were relatively high in populations from the ocean, large lakes and low-lying streams, and low in those from small lakes and isolated streams. Both deterministic (natural selection) and stochastic (founder effects and genetic drift) mechanisms can be invoked to explain these patterns. Morphologically and ecologically distinct benthic and limnetic sticklebacks within single lakes, and freshwater and marine sticklebacks within a stream, constituted genetically discrete populations. There was a striking congruence in the patterns of morphological and electrophoretic variability among the populations comprising such 'species pairs'. The results of this study are compatible with the suggestion that freshwater populations of the study area are polyphyletic, and have arisen independently from marine sticklebacks which invaded the region since the last ice age, about 10,000 years ago.
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 | 0,000 | 0,000 |
| Méta-épidémiologie (sens strict) | 0,000 | 0,000 |
| Méta-épidémiologie (sens large) | 0,000 | 0,000 |
| Bibliométrie | 0,001 | 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) | 0,001 | 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 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 ».