Mass migration, population genetics and historical population expansion in the Neotropical butterfly Kricogonia lyside (Lepidoptera: Pieridae).

Little is known of the migratory ecology and population genetics of the lyside sulphur butterfly Kricogonia lyside (Godart) (Pieridae: Coliadinae). Mass migrations involving huge numbers of these butterflies have long been known to occur in the southern USA, Mexico and Greater Antilles, but these reports have been based mainly on chance encounters. A review of the limited literature on migrations of K. lyside in North America is presented here, together with results from field observations of a recent mass migration in north-western Mexico. Overall, these data confirm that migrations of K. lyside are often unidirectional, but can change direction over relatively short time periods, and are most probably 'triggered' by substantial rainfall following a prolonged dry period. Several important questions on these enigmatic migrations, however, including, but not limited to, location of source populations, ultimate destinations, numbers of individuals involved and purpose, remain to be answered. Analysis of mitochondrial DNA barcodes revealed that genetic diversity of the cytochrome c oxidase subunit I (COI) gene is much higher in K. lyside than that seen in the long-distance migrating nymphalid butterflies, the monarch (Danaus plexippus) and painted lady (Vanessa cardui), and that a large historical population expansion occurred during the mid-Pleistocene. [ABSTRACT FROM AUTHOR]