Investigating adaptation in marine threespine stickleback (Gasterosteus aculeatus) recently isolated to Lost Lagoon, British Columbia
Bibliographic record
Abstract
Reduction in the number of lateral plates in Threespine Stickleback (Gasterosteus aculeatus) that have colonized freshwater habitats is a well-studied case of parallel evolution. Parallel evolutionary events provide insight into the processes driving adaptation by highlighting the contribution of natural selection to evolutionary change. Most studies have focused on threespine stickleback populations that have been living in freshwater since widespread glacial melting 10,000 to 20,000 years ago. I recently identified a population of marine threespine stickleback that have been sequestered in Lost Lagoon, BC, Canada since 1916 providing an opportunity to examine evolution on a contemporary time scale. In this thesis, I test the hypothesis that threespine stickleback in Lost Lagoon have adapted genetically and phenotypically to freshwater conditions because of changes in selective pressures following isolation to Lost Lagoon. I conducted genetic and phenotypic comparisons between Lost Lagoon and nearby marine and freshwater populations in Madeira Park, BC. Genetic comparisons involved examining divergence between populations at the ectodysplasin A (Eda) locus, the major genetic control for the number of lateral plates, and calculating neutral genetic divergence using FST from Pooled Sequencing results. Phenotypic comparisons were performed by using microcomputed tomography (µCT) to generate three-dimensional skeletal models that were landmarked to quantify shape phenotype. Results suggest that stickleback in Lost Lagoon have undergone considerable evolutionary change on a relatively short timeline and are in the midst of evolution transition. I also demonstrated the usefulness of this population in testing mechanisms driving selection because of the variation in Eda present on a controlled genetic background by testing the hypothesis that adaptation to freshwater is driven by increased escape response performance. Escape responses were stimulated and filmed in wild fish from Lost Lagoon and in a F1 generation raised in the laboratory. Results suggest that Eda does not contribute to variation in the kinematic variables measured. Collectively, the research in this thesis illustrates that Threespine stickleback in Lost Lagoon appear to be in the midst of evolutionary transition but the mechanistic connection between this transition and the Eda locus remains elusive.
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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) | 0.006 | 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".