A global-change winner? Global expansion potential, ecological drivers and hybridization risk of the disturbance-promoted honey locust (Gleditsia)

Rapid environmental change and anthropogenic activities are reshaping plant <br/>distributional patterns and facilitating novel species compositions. The disturbancetolerant, globally distributed Honey Locust (Gleditsia) provides a compelling case <br/>for studying these novel dynamics. In this study we assessed (1) the realized and <br/>potential distribution of the North American Gleditsia triacanthos in its native and <br/>introduced ranges, (2) ecological range determinants, (3) potential niche shifts <br/>between the North and South American populations of G. triacanthos, and (4) <br/>overlaps in the introduced distribution of G. triacanthos and native congeners, as an <br/>indicator of risks of hybridization or competitive exclusion. These analyses were based <br/>on species distribution modelling, using the Maximum Entropy algorithm. Habitat <br/>suitability of G. triacanthos was highest in regions with high Human Modification <br/>Index values, indicating anthropogenic disturbance as a major driver of its potential <br/>range. The results show a niche difference between the native North American and <br/>introduced South American populations of G. triacanthos, supporting high plasticity <br/>and local adaptive capacity as previously reported. Further, the results show wide <br/>potential for overlapping distributions between G. tricanthos and congeneric species <br/>outside North America, pointing to substantial potential for hybridization. This likely <br/>poses risks to the genetic integrity of geographically restricted taxa, such as G. <br/>caspica in the Caucasus region, but might also provide genetic diversity that could <br/>help local populations adapt to global change or, alternatively, create new invasive <br/>hybrid linages. Understanding the distributional dynamics and biotic interactions <br/>of globally expanding species like G. triacanthos is critical for anticipating ecological <br/>change and guiding adaptive conservation and management strategies.