Relationship between the location of Pleistocene refugia and geographic and environmental centrality in a plant-pollinator mutualism from Patagonia

Glacial refugia are habitats where species can persist during climate change, and they are of high conservation value due to their role as hotspots of genetic diversity. Therefore, it is relevant to understand factors that determine the distribution of these refugia across species’ ranges and of their mutualists. According to the CPH, as genetic diversity is highest in the geographic range centre of the species' distribution, it is expected that refugia coincide with this centre, if the geographic and environmental centroids are coupled. We proposed an integrative framework that combines genetic diversity, current and past distribution range, and historical ecological niche to investigate the association between Pleistocene refugia and geographic and environmental centrality in a plant-pollinator mutualism from Patagonia. We identified a clear pattern in which genetic diversity was negatively associated with distance to environmental centroids and positively with distance to geographic centres of Centris cineraria, Calceolaria polyrhiza, and their mutualistic interaction. Our results show that glacial refugia can be geographically peripheral but ecologically central, and that highly specialized mutualism would share the same refugia. Focusing on spatio-temporal dynamics of environmental rather than geographic centroids can contribute to a better understanding of aspects related to the conservation and evolution of population species.