Using genetic and morphological analysis to distinguish endangered taxa from their hybrids with the cultivated exotic pest plant Lantana strigocamara (syn: Lantana camara)

Abstract

Because highly invasive species can rapidly assimilate rare taxa, we questioned whether two Florida endangered Lantana depressa varieties existed 21 years after Sanders documented their widespread hybridization with exotic Lantana strigocamara, and whether morphological traits could accurately discriminate genetic individuals. Stepwise discriminant analysis of morphological characters discriminated the three taxa, correctly classifying 98, 91, 89% of L. strigocamara, L. depressa var. depressa, and var. floridana. Hybrids blurred taxonomic distinctions of varieties and reduced classification accuracy by 7–17%. Species-specific Random Fragment Length Polymorphism (RFLP-PCR) confirmed hybridization has occurred. Intersimple Sequence Repeat (ISSR) fingerprints analyzed with STRUCTURE identified three groups indicating introgression. Morphological traits significantly, but weakly correlated with q ratios (P = 0.0001; r 2 = 0.45). Although L. strigocamara introgression is widespread and ongoing, wild populations contain individuals that are predominantly L. depressa genome, supporting actions to remove adventive L. strigocamara, prevent its sale, and promote sales of genetically confirmed natives.