Patterns of Nuclear Genetic Variation in the Poecilogonous Polychaete Streblospio benedicti
Bibliographic record
Abstract
The evolution of marine larvae is replete with transitions in trophic mode, but little is known about how, at the genetic level, these transitions are achieved. Basic parameters, including the number of underlying loci, their molecular characteristics, and the population-genetic processes that drive transitions remain unknown. Streblospio benedicti, an abundant benthic polychaete with heritable poecilogony, provides a unique genetically tractable system for addressing these issues. Individuals of S. benedicti vary in diverse aspects of development. Some females produce small, planktotrophic larvae, whereas others produce large, yolky larvae capable of settling without feeding. Here, I present estimates of basic features of nuclear genetic variation in S. benedicti to lay the foundations for subsequent efforts to understand the genetic basis of poecilogony. Sequence of ∼20 kb of random nuclear DNA indicates that the nucleotide composition, at 62.1% A + T, is typical of lophotrochozoan genomes. Population-genetic data, acquired by sequencing two loci (∼2500 bp) in multiple animals of each developmental morph, indicate that the morphs exhibit very little differentiation at random loci. Nucleotide heterozygosity (θπ) is ∼0.5-1% per site, and linkage disequilibrium decays within a few kilobases (ρ ∼ 3 × 10(-3) per site). These data suggest that genetic mapping by association will require a high density of markers, but linkage mapping and identification of regions of elevated inter-morph differentiation hold great promise.
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 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) | 0.001 | 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 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".