Degeneration, Expression Evolution, and Functional Specialization of Young Sex Chromosomes in the Plant Rumex hastatulus
Bibliographic record
Abstract
Young Y chromosomes, such as those found in many plant species, provide valuable insights into the early stages of processes such as Y chromosome degeneration. Investigating these processes empirically may allow for evaluation of both classic and more recent theoretical models of sex chromosome evolution. In my thesis, I use new high-quality genomic resources along with large transcriptomic and genomic datasets to investigate sex chromosome evolution in Rumex hastatulus, a dioecious plant where the males have two Y chromosomes in one subtype (the XYY cytotype) and one Y chromosome in the other subtype (the XY cytotype). In Chapter 2, I show that significant Y chromosome degeneration resulting in gene loss and loss of synteny occurs at evolutionarily recent timescales (<10 million years) in R. hastatulus, but not at extremely short timescales (<200,000 years). In Chapter 3, I investigate the role of regulatory evolution in Y chromosome degeneration and found signs of ongoing Y chromosome expression loss associated with deleterious mutation accumulation, consistent with regulatory models of Y chromosome degeneration. I also found a lack of widespread transcriptional dosage compensation, which does not support theoretical predictions that early regulatory divergence can mediate sex linked region expansion. In Chapter 4, I focus on characterizing genes that remain on the Y, as they may play an essential role in functional specialization and male-specific development. I found an enrichment of unique genes on the Y sex-linked region, and increased Y-biased expression in pollen compared to leaves, which may indicate a role of pollen competition in Y gene evolution. Overall, my thesis contributes to our understanding of the timing of degeneration, the role of regulatory evolution and the evolution of functional specialization on the young plant Y chromosomes.
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".