The Roles of Life History and Mating System in Speciation: Genomic Evidence From the <i>Incarvillea sinensis</i> Complex
Bibliographic record
Abstract
The temporal sequence and mechanistic interplay between life-history and mating-system transitions in plants remain poorly understood. Here, we combine crossing experiments with population genomic analyses to investigate these processes in the Incarvillea sinensis complex (Bignoniaceae), which contains annual selfing and perennial outcrossing populations. Crossing experiments revealed complete post-zygotic isolation between annuals and perennials. Genomic data derived from de novo assemblies of annual and perennial individuals, along with SNP and chloroplast sequencing of 126 individuals from 30 populations, demonstrated strong genetic divergence between life histories, with no evidence of contemporary gene flow between them. Compared to perennials, annuals exhibited significantly reduced genetic diversity, elevated differentiation and a greater number of chromosomal rearrangements-particularly translocations. Divergence time estimates indicated that annual and perennial lineages split during the early Pleistocene (ca. 2.22 Mya), whereas the shift to selfing from outcrossing within the annual lineage was a more recent event, occurring during the late Pleistocene (~0.03 Mya). These results indicate that the mating-system shift was not the initial driver of divergence, and we infer that the life-history transition likely occurred earlier, although its precise timing could not be directly determined. Our findings support a two-stage model of divergence in which adaptation to seasonally arid environments first drove the evolution of annuality, initiating speciation through ecological isolation and genetic divergence. The subsequent evolution of selfing then likely further promoted reproductive isolation via both pre- and post-zygotic mechanisms, potentially accelerating rapid genomic differentiation and effectively completing the speciation process.
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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) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| 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".