Incorporating light pollution into projections of the future distribution of <i>Aspisoma sticticum</i> Gemminger, 1870 under climate change in South America

Abstract Climate change and light pollution are emerging stressors that can alter habitat suitability and disrupt reproductive signalling in fireflies; we evaluated their combined effects on the potential distribution of the spotted tortoise firefly Aspisoma sticticum Gemminger, 1870 (Coleoptera: Lampyridae) across South America. Using 337 filtered occurrences and three algorithms (GLM, Maxent and DOMAIN) in an ensemble, we modelled habitat suitability under two general circulation models (GCMs) (MIROC6, UKESM1‐0‐LL), two emission scenarios (SSP2–4.5, SS) and two periods (2041–2060, 2081–2100), comparing Clim + Physiography predictors with Clim + Physiography + Light predictors. Clim + Physiography ensembles predicted strong contractions by 2100, with losses of about 45%–80% of currently suitable area across GCM × scenario combinations, most severe in the Amazon, Caatinga and Cerrado, while southern South America and the Atlantic Forest coast emerged as relatively stable climatic refugia. Models including light pollution yielded higher stability of currently suitable areas (&gt;55%–80% of the range) and large gains of newly suitable habitat (~70%–90% of the current extent), especially in central and eastern South America, with light pollution emerging as the dominant predictor in Maxent. However, these apparent range expansions of suitable areas likely reflect light pollution acting as a proxy for anthropogenic landscapes and biased sampling, rather than a beneficial effect of light. This underscores the need for bias‐aware data collection, multi‐algorithm ensembles and algorithm selection to reliably forecast species responses to artificial illumination under environmental change, with Atlantic Forest refugia remaining key conservation priorities in South America.