Moving with your mutualist: predicted climate-induced mismatch between proteaceae species and their avian pollinators

Abstract

Aim: Climate change influences species distribution in space and time, but predict ing the overlap in the range of interacting species under different climate scenarios remains a challenge. Here, we explore how climate change influences shifts in species ranges among mutualists. Location: Cape Floristic Region (CFR), South Africa. Taxon: Proteaceae and Passeriformes. Methods: We used machine-learning algorithms (random forest and boosted regression trees) and regression model (generalized additive models) to predict range shifts of 11 bird-pollinated Proteaceae species, combined occurrence prediction of 71 bird-pollinated Proteaceae and their two most important, endemic, pollinator bird species. We determined the degree of overlap in geographical ranges of nectar feeding birds and Proteaceae under different climate scenarios. Species ranges were projected to the years 2050 and 2070 using representative concentration pathways (RCP) 4.5 and 8.5 and three global climate models. Results: The majority of Proteaceae species in our model are predicted to experience range contractions, which ranged from 1% under 2050 RCP 4.5 CCSM4 to 79% under 2070 RCP 8.5 CNRM-CM5 climate scenarios, leading to 55% and 62% range loss for Cape sugarbird and orange-breasted sunbird, respectively, under extreme climate scenarios. Proteaceae species are predicted to experience least overlap with nectar feeding birds in the northern and eastern range under future climate scenarios. Main Conclusion: Climate change threatens species occupying the mountain range of the northern limit and other regions of the CFR. Reduced range overlap of mutualists may have significant implications for the reproduction and persistence of Proteaceae. We suggest active monitoring of Proteaceae populations in regions where species are predicted to lose their range, particularly so for threatened species with small ranges.