Barriers evolving : reproductive isolation and the early stages of biological speciation
Bibliographic record
Abstract
The process of speciation can be complex and represents the ultimate basis for biodiversity on the planet Earth. The contribution of various intrinsic reproductive barriers and their underlying phenotypic mechanisms were studied using two Drosophila model systems: the cactophilic sister species Drosophila arizonae and D. mojavensis, from the deserts of Mexico and the Southwestern USA, and populations of the circumboreal, hydrophilic fly, Drosophila montana, from North America and Northern Europe. Levels of premating isolation between D. arizonae and D. mojavensis as well as between populations of D. montana were significant and sensitive to experimental design. Further investigations of intrinsic barriers to gene flow among populations of D. montana from Canada, Finland and the USA showed that different mechanisms (premating vs. postmating) act with different strengths depending on the populations. Premating isolation was significant between all populations and postmating isolation was strongest in crosses between American (Colorado) females and Canadian (Vancouver) males. This was found to be due to a postmating, prezygotic barrier; while sperm from Canadian males were successfully transferred and stored after matings with American females, the majority of these eggs were not fertilized. The last study in this thesis aimed to determine whether cuticular hydrocarbons might play a role in sexual selection in D. montana. The study revealed significant variation in cuticular hydrocarbons among populations and between the sexes, as well as correlations between particular principal components or individual hydrocarbon peaks and behavioural measurements relevant to sexual selection. These effects appeared to be strongest in the Canadian population of the species. Thus, cuticular hydrocarbons may be involved in sexual selection within and sexual isolation between populations, although more direct tests using manipulation of CHCs are still needed.
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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 | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 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".