Reassessing the Status of a Data-Deficient Insular Population of a Critically Endangered Species

The conservation status of more than 160,000 species has been assessed following IUCN guidelines, with greater than 13% considered data deficient. Maintaining an accurate understanding of native populations is challenging, especially for species with geographically large or discontinuous insular ranges. Here we assessed a data deficient population of a critically endangered reptile within the Caribbean biodiversity hotspot. We surveyed the island of Antigua for three weeks to assess whether the native Iguana delicatissima remains present. Morphological data from 98 observed and 29 captured iguanas showed no sign of pure remaining I. delicatissima; whilst 19 individuals had some morphological features of I. delicatissima. Sequence data and discriminant analyses of 17 microsatellite loci assigned all captured iguanas to I. iguana, although the presence of two I. delicatissima alleles are indicative of an old introgressed population. The only present mtDNA haplotype matched to the non-native iguana population on Grand-Terre, Guadeloupe. This provides genetic evidence of hurricane-mediated translocation as proposed happened in the aftermath of two 1995 hurricanes when debris-rafts with iguanas landed on Anguilla, Barbuda, and Antigua. The rapid decline of I. delicatissima places urgency on finding and conserving any surviving remnant populations, which we show are likely absent from Antigua, though we cannot rule out the presence of a few individuals.