Painted Lady Butterfly Migration Driven by Environment, Study Finds
Why in the news
Research reported in PNAS Nexus showed that painted lady butterflies do not follow genetically fixed migration patterns, unlike what is often assumed from birds.
Key facts
- Short-distance and long-distance migrants belong to one interbreeding genetic population.
- The full route of about 15,000 km is covered across 8-10 generations; individuals do not return to the same breeding site.
- Stable isotopes of hydrogen and strontium in wings revealed origins.
- Wing morphology had no link to distance flown.
- Some butterflies that flew 4,000 km had barely worn wings, so wing-wear is not a reliable sign of long flight.
Migration pattern
| Season | Movement |
|---|---|
| Spring | From the Sahara northward over the Mediterranean into southern Europe, where they breed |
| Autumn | The next generation flies south through Spain and Italy to North Africa |
Method
- Tracking across Benin, Senegal, Morocco, Spain, Portugal and Malta over several years.
- Genetic data combined with isotope markers.
- Isoscapes, i.e. isotope distribution maps of Europe and North Africa, estimated distances.
Significance
- Knowing which environmental factors steer migration may help predict insect behaviour under climate change.
- Next steps: compare insect and bird migration, and study butterflies from the U.K. and Japan.
Exam angle
- Species: Vanessa cardui (painted lady).
- Journal: PNAS Nexus.
- Related terms: isoscape, stable isotope analysis, multi-generational migration.