The evolution of sexual bill-size dimorphism in shorebirds: a morphometric test of the resource partitioning hypothesis
Bibliographic record
Abstract
Question: Is sexual dimorphism in shorebirds an adaptation to reduce resource competition between males and females? Hypothesis: If selection for resource partitioning between the sexes has contributed to dimorphism, then the degree of sexual size dimorphism (SSD) in resource-exploiting characters – such as those related to feeding – should exceed that expected from sexual selection alone. Data: Morphometric data from 151 species of shorebirds (Charadriiformes). Methods: We compared the degree and direction of SSD between a resource-exploiting trait (bill length) and a non-resource-exploiting trait (body size). If bill-SSD exceeds body size-SSD, then resource partitioning may contribute to morphological differentiation of the sexes in shorebirds. We also tested whether SSD is more pronounced in migrant than non-migrant species. Conclusions: From species level data it appears that bill dimorphism is more pronounced than body size dimorphism, and is more common in migrant than non-migrant shorebirds. This observation from extant taxa suggests a role for resource partitioning in promoting SSD. The phylogenetic effect on both of these correlations is significant, however, to the extent that shared ancestry, rather than contemporary selection, is sufficient to explain why resourceexploiting traits and migrants are more sexually dimorphic.
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 | 0.003 | 0.005 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.002 |
| Science and technology studies | 0.001 | 0.002 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.001 | 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".