Low Variation in a Y‐Chromosomal Growth Hormone Pseudogene Relative to its Functional Autosomal Progenitor Gene in Chinook Salmon
Bibliographic record
Abstract
Abstract Most fish species do not have single‐chromosome‐based sex determination or display cytologically distinguishable sex chromosomes. The selective forces acting on homologous sequences in diploid autosomal versus haploid sex‐chromosomal regions are expected to be distinct and thus to differentially influence genetic variation. In Chinook Salmon Oncorhynchus tshawytscha, the Y chromosome possesses a growth hormone pseudogene (ghp) that is linked to the sex‐determination locus and is derived from the functional autosomal growth hormone 2 gene (gh2). Thus, examining these two paralogues provides a model with which to study the forces affecting the persistence of genetic variation between sex‐linked and autosomal loci among individuals in Chinook Salmon populations. We characterized single‐nucleotide polymorphisms in a 1.6‐kb contiguous homologous region in gh2 and ghp in 315 individuals from 19 Chinook Salmon populations ranging from Russia to Alaska, British Columbia, and California. The ghp sequence was highly similar among individuals and populations, with variant haplotypes being detected in only 5.4% of individuals and restricted to just two populations. In contrast, gh2 variants from the most common haplotype were found in 46.7% of individuals. We detected more sites of variation in ghp (nine positions, five haplotypes) than in gh2 (three positions, five haplotypes), but these were restricted to just four genotypes for ghp, compared with nine for gh2. Selection may have caused a single Y chromosome to become fixed among most populations in this species, while the variation at the gh2 locus is maintained under diploid autosomal conditions. Since the ghp locus variants are not likely to be directly associated with strong functions, other linked Y‐chromosomal loci may have important functions that, when selected, cause Y chromosomes to either be damaged and rapidly eliminated or to have enhanced fitness and sweep through the species. Whether such loci include the sex‐determination locus itself or other functional loci is not yet known.
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 | 0.000 |
| 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) | 0.001 | 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".