REPRODUCTIVE ECOLOGY AND GENETICS OF PLANT INVASIONS: A CASE STUDY OF LYTHRUM SALICARIA (PURPLE LOOSESTRIFE)
Bibliographic record
Abstract
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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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.005 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one teacher head, not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".