Overcoming environmental and morphological constraints: egg size and pelvic kinesis in the smallest tortoise, <i>Homopus signatus</i>
Bibliographic record
Abstract
The small tortoises of southern Africa include the only testudinid taxa that produce single-egg clutches. This group includes the world's smallest tortoise, Homopus signatus (Gmelin, 1789), which inhabits a harsh, arid environment. Climate and body size may influence reproductive output, so we hypothesized that the east–west aridity gradient in southern Africa affects egg and clutch size of the small indigenous tortoises, and that the morphology of H. signatus constrains egg size, preventing the formation of optimal eggs. Here we show that aridity and unpredictable rainfall determine which of these tortoise taxa produce single-egg clutches. Taxa in less predictable environments produce larger eggs relative to body size than do taxa in more predictable environments. Homopus signatus produces the largest egg relative to body size, probably to enhance offspring survival in its harsh environment. Body size, pelvic aperture size, and the narrow anal gap of H. signatus appear to constrain egg size. Despite these constraints, females produce rigid-shelled eggs larger than the pelvic canal and use pelvic kinesis to pass eggs at oviposition; both features are unknown in other chelonians and emphasize the selective advantage of large eggs to H. signatus.
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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 | 0.000 | 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".