Rare and common species are doomed by climate change? A case study with neotropical butterflies and their host plants

Climate change is currently considered one key threat to biodiversity. Species with a restricted distribution possibly will be more affected than those with wide ranges. Climate change can potentially affect both herbivores and their host plants and reduce their geographical ranges. The nature and intensity of their responses, however, may not necessarily match. We investigated the synergistic effects of climate change on two Neotropical butterfly species and their respective host plants at the end of twenty-first century. The species selected contrast in distribution extent, feeding habits and conservation status: Battus polystictus is widespread, oligophagous and common and Parides ascanius has a restricted distribution, is monophagous and is listed as vulnerable in the IUCN red list. Maps of the potential distribution of the butterflies and their host plants, as well as maps showing the changes in the ranges, in overlap area and direction of shifts were produced. Under forecasted climate change, all ranges and interaction areas decreased and the impacts were proportional to the intensity of change in future scenarios, either when compared all together or pairwise (p < 0.001). Based in our results estimation of climatically suitability, the monophagous butterfly with restricted distribution did suffer more severely these effects than the widespread generalist species. We did not anticipate, however, the possible strength of the predicted effects. Under the conditions modelled, P. ascanius would probably find no suitable conditions for occurrence, irrespectively of its host plant, and might go extinct. B. polystictus , on the other hand, suffered marked decreases in suitable area (46% for RCP4.5 and 91% for RCP8.5) and dramatic southward shifts (> 1439 km for RCP4.5 and > 1956 km for RCP8.5) on its range. This effect is further worsening because although most host plants are also much affected by the changes, the shift in their ranges is on average much smaller and each species responded in subtly different ways to the changing conditions, so that most of their future range may be spatially incompatible with the B. polystictus. We propose that the extinction risk of P. ascanius should be adjusted to critically endangered and point that species interactions and climate change must be accounted for in conservation planning. Implications for insect conservation The assessment carried out in this study contributes to the knowledge of climate change scenarios of butterfly species correlated with their host plants until the end of this century. These results can propose priority sites for conservation efforts like contribute to change status of P. ascanius to critically endangered, actually listed as vulnerable on the IUCN red list.