Species discovery and evolutionary history of marine gregarine apicomplexans
Bibliographic record
Abstract
Gregarine apicomplexans are a diverse but poorly understood group of single-celled parasites infecting a wide range of invertebrates in marine, freshwater and terrestrial environments. My thesis focuses on marine gregarines. Gregarines from marine hosts are unique because some (archigregarines) have maintained a set of pleisiomorphic characteristics from the ancestor of gregarines and apicomplexans alike. Other lineages of marine gregarines (eugregarines) are thought to have been modified from this archigregarine morphotype, and represent a wide-range of diversity with regard to general morphology, motility, and feeding strategies. My work has broadly applied molecular phylogenetics to novel species of marine gregarines from areas around British Columbia, Canada and Okinawa, Japan, with the goal of placing the evolution of gregarines in a molecular phylogenetic context. I amplified mainly SSU rDNA from a distinct life history stage (trophozoites), and coupled that with morphological data I gathered from light, confocal, as well as electron microscopy. Although my work was unable to resolve deep phylogenetic relationships among gregarines (and apicomplexans), this work did improve our understanding of evolution within gregarines. With the discovery of Veloxidium leptosynaptae from the gut of an echinoderm in Bamfield, British Columbia, and Surculinium glossobalanae from a hemichordate in Okinawa, I was able to show the paraphyly of the archigregarine morphotype, and polyphyly of other gregarine lineages, including some groups of neogregarines and eugregarines in terrestrial and freshwater environments. With the description Polyplicarium, my work uncovered and identified an ambiguous environmental sequence clade and, along with other work on Selenidium, was able to show that SSU rDNA can be reliably isolated from single cells as a method for delimiting closely related or morphologically similar species. In my final data chapter, I conducted an in-depth study on the morphology and molecular phylogenetic relationships between two sister species from the same host, Selenidium terebellae, and a newly discovered species, Selenidium melitzanae. Results from this data gave me the first opportunity to compare character evolution and niche partitioning among closely related gregarines, and provided another example of convergence of the eugregarine morphotype.
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 | 0.000 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.002 | 0.001 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.000 | 0.001 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 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".