A single nucleotide change underlies the genetic assimilation of a plastic trait
Bibliographic record
Abstract
Genetic assimilation – the evolutionary process by which an ancestral environmentally sensitive phenotype is made constitutive – is a fundamental concept in biology. Its evolutionary relevance is debated, and our understanding of its prevalence, and underlying genetics and molecular mechanisms, is poor. Matricidal hatching is an extreme form of maternal provisioning induced by adverse conditions, which varies among Caenorhabditis elegans populations. We identified wild isolates, sampled from natural populations across multiple years and locations, that express a derived state of near-constitutive matricidal hatching. A single amino acid change in kcnl-1 , encoding a small-conductance calcium-activated potassium channel subunit, explains most of this variation. A gain-of-function mutation altering the S6 transmembrane domain causes inappropriate activation of the K + channel, leading to reduced vulval muscle excitability, and thus reduced expulsion of embryos, irrespective of environment. Using reciprocal allelic replacements, we show that this amino acid change is sufficient to induce constitutive matricidal hatching whilst re-establishing the ancestral protein abolishes matricidal hatching and restores egg-laying, thereby doubling lifetime reproductive fitness under benign conditions. While highly deleterious in the laboratory, experimental evolution showed that KNCL-1(V530L) is maintained under fluctuating resource availability. Selection on a single point mutation can therefore underlie the genetic assimilation of an ancestrally plastic trait with drastic life-history consequences.
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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 | 0.000 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.002 | 0.001 |
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".