Tetraploids of an invasive clonal shrub, <i>Lantana camara</i> , present greater invasiveness than diploids

Abstract Compared with diploids, polyploids exhibit distinct biological traits and invasion strategies, often conferring enhanced invasive potential. However, the impact of polyploidy on the invasiveness of shrub species remains insufficiently explored. In this study, the role of ploidy in the invasiveness of Lantana camara, a woody invasive clonal shrub widely distributed in tropical and subtropical regions, was investigated. The cytotypes of eight wild L. camara populations across Hainan Island were analyzed. A comprehensive comparison was conducted between diploid and tetraploid plants to assess niche breadth, clonal growth patterns, morphological traits, and genetic diversity. Additionally, common garden experiments were performed to evaluate the morphological and physiological responses of both cytotypes to environmental fluctuations. Tetraploids accounted for 85% of the individuals, and were distributed across seven populations, whereas diploids represented only 15% and were restricted to a single population. Compared with diploids, tetraploids exhibited: (1) broader ecological niche occupancy, (2) significantly higher genetic diversity, (3) more variable growth forms in natural habitats, (4) increased seed production, and (5) greater phenotypic plasticity under experimental conditions. These findings suggest that polyploidy contributes substantially to the invasive success of L. camara by enhancing adaptability and reproductive capacity. Overall, the results of this study underscore the role of tetraploids in promoting invasion in this tropical shrub species and highlight the importance of cytotype differentiation in understanding invasion dynamics.