Minimum sample size, population genomics and morphological variation in the terrestrial gastropod Webbhelix multilineata (Mollusca, Polygyridae)
Notice bibliographique
Résumé
Patterns in evolutionary and ecological biology help shape our view of the physical world both in the present and its past. Biogeographical studies in particular afford understanding of how biological systems have been shaped by processes over geological time, both genetically and morphologically. Some systems, like terrestrial gastropod mollusks, are well suited for these types of studies owing to their near ubiquitous occupation of terrestrial habitats, while also individually being very locally restricted and having poor reproductive dispersal. A notable species is the striped white-lip snail Webbhelix multilineata, a morphologically charming and biogeographically interesting study system because of its somewhat unusually broad geographic range spanning large regions of North America previously glaciated and unglaciated during the Pleistocene. It is also quite restricted to moist, shaded riparian woodlands, a historically profuse habitat that has been largely lost and become highly fragmented due to human development. These features and others make Webbhelix an enticing system for biogeographical and population study, and the chosen focus of the studies presented here. While there are many different molecular and morphological approaches that can be taken to pursue such studies, this dissertation focused primarily on the generation and use of genomic data for a non-model system, and secondarily on generating and utilizing morphological data, to accomplish three major aims: (1) test for a minimum sample size to accurately estimate basic population genomic parameters in Webbhelix multilineata; (2) generate the first genomic dataset for Webbhelix and utilize it for population genomic assessment, as well as coalescent simulations to assess models of post-glacial refugial expansion; and (3) test variation in Webbhelix shell size and brightness within the context of established ecogeographic patterns. Addressing the first aim using SNPs generated through a ddRADseq approach showed that as few as 6 individuals per sampled locality was sufficient to accurately estimate observed and expected heterozygosity, inbreeding coefficient, and pairwise differentiation in Webbhelix. Pursuit of the second aim netted an 8,480 SNP dataset composed of 18 sample localities from across the species range, and its assessment for population genomic structure revealed 4 population clusters: two Midwestern clusters, a southern Mississippi River cluster, and an eastern cluster on the shores of Lake Erie in Ontario. Estimates of genetic diversity found it was highest in the southern-most sampled localities and generally decreased further north and away from the Mississippi River, indicative of serial founder effects resulting from range expansion. Analysis of coalescent simulations suggested that post-glacial range expansion in Webbhelix occurred along major river corridors rather than openly in all directions, and that expansion either began as early as some 20,000 years ago around the LGM or a more northerly refugia existed for this species than initially considered. Lastly, work toward the third aim resulted in a moderately strong negative correlation being found between shell size and latitude in Webbhelix, indicating a pattern described by a reverse Bergmann cline. Additionally, a weak positive correlation was found between shell brightness and latitude, suggesting (with heavy caveats) that Webbhelix may exhibit the pattern described by Gloger’s ecogeographic hypothesis.
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 ».