Geographic comparison of seasonal migration events of the large white butterfly, Pieris brassicae

Abstract

1. The multivoltine butterfly Pieris brassicae (Linnaeus) inhabits most climatic zones in Europe and Asia. Its regional populations are adapted to the respective climatic conditions and hibernate in those regions. Yet how these adaptations are stabilised in spite of the species' regular migration events is unclear.2. In this study, significant differences were found in the preferred flight direction of P. brassicae depending on the season and the butterfly's geographic origin. The individual flight behaviours indicated that flight direction is a heritable character.3. The bivoltine population from northern Germany undertook a typical return flight in the second generation of the year. This reverse flight was induced by the developmental mode of the caterpillars. A diapause in the pupal stage triggered a northward migration, and a non‐diapause a southward migration.4. In contrast to bivoltine populations, the second generation of multivoltine populations maintained the direction of the hibernating generation.5. A unique situation was determined for the population from the northern coast of Spain. The North Sea seemed to be a migration barrier that forced an adaptation, with the first generation flying southeastward, and the second generation northeastward.6. The flight pattern of at least some of the investigated populations suggests that, after their yearly migration, the descendants of a local population are able to reach the home range of their ancestors again.