Genetic diversity and propagule pressure: determinants of invasion success?
Bibliographic record
Abstract
Ongoing invasions by non-indigenous species (NIS) have fundamentally modified aquatic communities in Canada and abroad. The process of biological invasion encompasses a series of stages and embedded barriers, which NIS must pass through from donor to recipient regions. Establishment of NIS and their attendant impacts call for detailed studies on factors influencing invasion success, including the role of genetics. Introduced populations may experience genetic bottleneck during invasion, hence propagule pressure and associated genetic diversity are relevant considerations. High propagule pressure may enhance genetic diversity by representing a larger pool of propagules from donor region, and mitigates the effect of demographic stochasticity. Moreover, high genetic diversity allows for rapid response to changing environments. My goal in this dissertation was to characterize genetic diversity of aquatic NIS in successfully established and pre-introduced populations. Exploring the invasion genetics of the comb jelly Mnemiopsis leidyi (chapters two and three), I identified two separate pathways from North America to two regions of Europe, with hub-and-spoke dispersal from each initial colonization site. Then, I explored vector activity along possible invasion pathways of golden mussel Limnoperna fortunei in Asia and South America. My findings (chapter four) demonstrated that more diverse introduced populations of L. fortunei likely received higher propagule pressure than less diverse ones, indicating correspondence between genetic diversity and vector activity. The level of genetic diversity in introduced populations was at same, or higher, relative to native populations (chapters two to four). Furthermore, I explored the development of a genetic bottleneck prior to an introduction event using Ion Torrent technology to sequence small subunit ribosomal DNA fragments (chapter five) in zooplankton community resident in ballast water of an operating vessel. The number of Operational Taxonomic Units decreased throughout trans-Atlantic voyages, indicating developing genetic bottlenecks. Results provide empirical evidence for attenuation of genetic diversity prior to discharge of propagules, highlighting the role of pre-introduction phenomena in shaping genetic composition of introduced populations. This dissertation demonstrates the link between genetic diversity in source and recipient populations, and its relationship to vector activity. Future studies may clarify the relative roles of pre- versus post-introduction phenomena in influencing genetic composition of introduced populations.
Fetched live from OpenAlex and de-inverted. Abstracts are not stored in this database: the inverted indexes are 8.6 GB of the frame’s 9.3 GB of text, and the host has 13 GB free.
How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.001 | 0.003 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.003 | 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 source (direct Gemma or distilled Codex), 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".