Not one but two: examining the genetic origin and characterization of the non-native spectacled caiman (Caiman crocodilus) in Florida

Abstract

The US state of Florida is home to an alarmingly large number of invasive species, many of which have proven detrimental to native ecosystems. Biological invasions of reptiles in particular have been a major concern in recent years. The spectacled caiman (Caiman crocodilus) was first introduced from Latin America to Florida in the 1950’s. Given there are now established breeding populations across southern Florida, there are ongoing efforts to control them. Therefore, there is a need to understand this species’ natural history and introduction pathways. Previous studies have cited the Caribbean Coastal region of Colombia as a primary, and possibly exclusive, origin of C. crocodilus in Florida, and the species was identified as belonging to the C. c. fuscus molecular lineage. However, previous genetic sampling has been limited and may have been biased by small sample sizes and limited geographic scale. We collected 27 genetic samples from caimans captured in Florida, and sequenced the mitochondrial genes, Cytochrome oxidase I (COI) and Cytochrome B (CytB) for comparison with homologous gene fragments available for the species at GenBank. We found genetic evidence for multiple introduction events and the taxonomic classification of the Florida caimans as two distinct molecular lineages (C. c. fuscus and C. c. crocodilus) originating from at least two different regions: the Magdalena River Basin in Colombia and the Upper Branco River Basin in northern Brazil. This study helps to elucidate the genetic history of Florida caimans and provides valuable insight for population management of the species in Florida.