The Buckeye butterflies (genus Junonia) from Florida, USA, can be used as a model for studying colonization, establishment, and introgression of invasive insect species

Invasion biology focuses on understanding the arrival of non-native species into new habitats, including dispersal events, secondary contact zones, and hybridization. The buckeye butterflies (genus Junonia) of Florida, USA have experienced at least two invasion events during their history. It is thought that Junonia coenia was resident in Florida before the last glacial maximum, approximately 11,000 years ago. This species is polyphagous and distributed throughout the state. The first invasion event is thought to have occurred approximately 3,000 years ago when J. evarete (a monophagous mangrove-feeding species whose habitat is restricted to coastal areas) colonized Florida from the Caribbean. The second invasion event occurred approximately 50 years ago when J. genoveva (a polyphagous tropical species whose habitat in Florida is restricted to the most southern frost-free zone where its larval hosts can persist) colonized Florida from the Caribbean. This has led to habitat overlap of all three species. Hybridization occurs readily in the laboratory, and occurs naturally at some frequency between these species in the wild. Specimens are available for all three species from Florida and the Caribbean for the last 100 years. Diagnostic morphological and molecular markers exist for determining what Junonia have Caribbean ancestry, allowing us to observe the invasion and creation of a secondary contact zone over time and space. Using biogeography and population genetics, we have tracked the most recent invasion of Junonia as it colonized Florida. Although Junonia is not an agricultural pest, it can be used as a model for invasive species.