Future at risk? Specialized flagship herbivores threatened by climate change in the Atlantic Rainforest

Abstract

Predictive niche modeling studies suggest significant biodiversity loss under climate change scenarios, indicating that species currently classified as least concern may face extinction risks. Here, we assessed two flagship butterfly species endemic to the Atlantic Forest: Arcas ducalis and Cyanophrys bertha. Both species have previously been listed as regionally threatened, and C. bertha is considered ’Vulnerable’ (VU) by the International Union for Conservation of Nature (IUCN), although both are now classified as ’Least Concern’ (LC) by Brazilian government. It remains unclear whether these species are naturally rare or difficult to detect. Assessing the effects of climate change on their conservation status and dispersal potential may help establish more accurate threat categories. This study aimed to evaluate the effects of climate change under two scenarios (SSP245, optimistic; SSP585, pessimistic) for two future periods. The results indicate that A. ducalis may experience a range reduction of over 46%, with a decline of more than 40% in interaction with one of its host plants under the pessimistic scenario. Conversely, C. bertha could be classified as ’Near Threatened’ (NT) due to a range reduction of over 66% and a decrease of more than 89% in interaction with one of its host plants in the same scenario. Representation within Conservation Units (CUs) suggests that both species will maintain adequate range coverage only under current conditions, with significantly reduced coverage in future scenarios. Given these findings, stronger measures, such as incentives for establishing and maintaining protected areas, are essential for conservation of these flagship species.