Isotopic (δ2H and δ13C) tracing the provenance and fate of individual fatty acids fueling migrating animals: A case study of the monarch butterfly (Danaus plexippus)
Bibliographic record
Abstract
Introduction Among long-distance migratory insects, the monarch butterfly ( Danaus plexippus ) is one of the most iconic, whose journey is fueled by nectar from flowering plants along the migratory route which may involve up to 3,500 km. Understanding how and where monarchs obtain their dietary resources to fuel migratory flight and ensure overwintering stores would provide new insights into the migratory strategy of this species and subsequently help focus conservation efforts. Methods This pilot study was designed as a first attempt to assess the composition, dynamics, and isotopic (δ 2 H, δ 13 C) composition of essential and non-essential fatty acids (FA) acquired or manufactured de novo from larval host milkweed ( Asclepias spp.) by monarch butterflies and from adult emergence to overwintering. Results Data from controlled laboratory isotopic tracer tests suggested that adult monarchs convert their dietary energy mainly into 16:0 and 18:1 fatty acids and store them as neutral lipids in their abdomen. FA isotopic composition reflects not only dietary sources but also subsequent isotopic fractionation from metabolism. On the other hand, δ 2 H values of essential omega-3 fatty acid alpha-linolenic acid (ALA) correlated with δ 2 H Wing , as markers of an individual’s geographic origin and indicated the importance of larval diet. Additionally, in wild-type females, high isotopic fractionation in δ 13 C ALA between neutral and polar lipids might indicate increased bioconversion activity during gravidity. Finally, δ 2 H LIN showed positive H isotope fractionation from larval dietary sources, indicating that catabolic processes were involved in their manufacture. Furthermore, δ 2 H LIN showed a negative correlation with δ 2 H Wing values, which could potentially be useful when investigating individual life-history traits, such as migratory catabolic efforts or periods of fasting. Discussion This interpretation was supported by significant larger variations in δ 2 H LIN and δ 2 H LIN overwintering monarchs compared to other FA. Altogether, our results provide the first evidence that the H isotopic analysis of individual fatty acids in migrating and overwintering monarchs can be used to infer the nutritional history of individuals including the provenance of nectaring sites used to fuel key life history events.
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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 | 0.001 | 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 | 0.001 | 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) | 0.000 | 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 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".