VARIABLE PREDATION REGIMES PREDICT THE EVOLUTION OF SEXUAL DIMORPHISM IN A POPULATION OF THREESPINE STICKLEBACK
Why this work is in the frame
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Bibliographic record
Abstract
Sexual dimorphism is widespread in nature and can be influenced by sex-specific natural selection resulting from ecological differences between the sexes. Here we show that contrasting life-history pressures and temporal shifts in ecology can exert a strong influence on the evolution of sexual dimorphism. The bony spines exhibited by stickleback are a defense against open-water avian predators but may be detrimental against benthic macroinvertebrate predators. Female stickleback from a coastal lake in western Canada occupy a more open-water ecological niche and exhibit greater dorsal and pelvic spine number than males, but the magnitude of these differences varies among life-history stages, seasons, and years. Ecological data on diet and parasite load and 62 seasonal estimates of selection over a 15-year period show that selection favors increased spine number in females and decreased spine number in males, but only when pronounced ecological differences between the sexes results in differential exposure to the two, divergent predation regimes. Thus occasional sex-reversals in ecological niche reversed the mode of selection. These processes caused a predictable response in the subsequent generation, indicating that divergent predation caused evolutionary change in dimorphism. However, temporal oscillations in sex-specific selection resulted in no net change in sexual dimorphism over the 15-year study period, indicating that fluctuations in directional selection can be responsible for long-term stasis. Replicated shifts in selective regime can demonstrate the primacy of ecological processes in driving evolution and our results illustrate how such shifts are detectable using long-term monitoring of natural populations.
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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 | 0.001 |
| 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) | 0.000 | 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 it