Climate Change Impact on the Potential Distribution and Invasion Risk of Tetramorium caldarium (Roger, 1857): A...

Climate change is reshaping global species distributions and altering invasion dynamics, yet our understanding of how thermophilic invasive species will respond to future climatic conditions remains incomplete. We employed Maximum Entropy (MaxEnt) species distribution modeling to evaluate current and future suitable habitat for Tetramorium caldarium (Roger, 1857), a pantropical tramp ant species with established exotic populations across six continents. Three hundred and forty-six filtered occurrence records and five bioclimatic variables (bio_1, bio_4, bio_7, bio_11, bio_12) were selected through correlation analysis. Models were projected onto future climate surfaces using MRI-CGCM3 outputs for two Representative Concentration Pathways (RCP 2.6 and RCP 8.5) at 2050 and 2070. The model demonstrated excellent predictive performance (AUC = 0.942, TSS = 0.68), revealing that T. caldarium currently occupies extensive suitable habitat across tropical and subtropical regions between 30° N and 30° S. Three-dimensional niche analysis demonstrated remarkable climatic breadth, with the species occurring across temperature gradients from 14°C to 29°C and precipitation regimes from 500 to 3500+ mm annually. Jackknife analysis revealed that temperature seasonality (43.7%) and coldest quarter temperature (25.9%) were primary limiting factors, while precipitation contributed minimally (4.5%). Future projections indicated relatively stable core distributions through 2070, with net habitat gains ranging from 275,000 km² (RCP 2.6, 2050) to 630,000 km² (RCP 8.5, 2070). Southern China, southeastern United States, Mediterranean Basin, and northern Argentina were identified as high-risk regions for future spread. T. caldarium possesses sufficient climatic niche breadth to maintain its spread potential despite climate change, with warming temperatures creating new opportunities in temperate regions. These findings emphasize that preventing human-mediated dispersal remains more critical than managing climate-driven range shifts for this globally significant invasive species.