REPRODUCTIVE ECOLOGY AND GENETICS OF PLANT INVASIONS: A CASE STUDY OF LYTHRUM SALICARIA (PURPLE LOOSESTRIFE)
Notice bibliographique
Résumé
Biological invasions provide a valuable context for studying contemporary evolution. Because reproduction is a key process determining invasion success, investigations of the reproductive ecology and genetics of populations are particularly insightful. My Ph.D. thesis is comprised of five inter-related studies on Lythrum salicaria (purple loosestrife), a tristylous plant from Eurasia that has invaded wetlands in North America during the past 150 years. The specific questions I addressed, using computer simulations, surveys of natural populations, and glasshouse and field experiments, concerned the mechanisms governing the frequencies of mating types in populations, the characteristics and functional significance of partial self-incompatibility, the influence of floral morph structure and demography on mating and fertility, and the occurrence and significance of inbreeding depression for invading populations.\nStochastic computer models incorporating morph-specific self-compatibility and tetrasomic inheritance revealed patterns of morph-frequency variation and asymmetric morph loss consistent with data from L. salicaria, including a survey I conducted in Ontario of 114 populations that revealed stochastic loss of the S-morph from small populations. Glasshouse experiments involving controlled self- and cross-pollination demonstrated that ~34% of L. salicaria plants exhibited partial self-incompatibility, that this trait was weakly heritable, and was stable in expression over two years. Progeny testing of open-pollinated families in six populations and isolated plants in a field experiment revealed high rates of inter-morph mating demonstrating that L. salicaria is robust to demographic variation associated with colonization. Cumulative estimates of inbreeding depression (δ) in a four-year experiment, three under field conditions, revealed δ = 0.48 and 0.68, depending on how multiplicative fitness was estimated. The values were consistent with the outcrossed mating system of populations and high enough to oppose the spread of self-fertilization, unless pollinators or mates limit fertility, but lower than is frequently reported in other outcrossing plant species.\nIn summary, this research provides novel information on the mechanisms that maintain tristyly in invasive populations of L. salicaria, despite the occurrence of partial self- incompatibility. High rates of inter-morph mating promoted by reliable bee-mediated pollinator service limit opportunities for the breakdown of the polymorphism, an evolutionary transition that has commonly occurred in other invasive tristylous species.
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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) | 0,005 | 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 ».