European mushroom assemblages are phylogenetically structured by temperature

Global warming affects species composition. To increase our ability to predict future assemblages, we require a better understanding of the link between species occurrence and the thermal environment. Thermal environments can be characterized by annual mean temperature and intra-annual temperature variability (hereafter termed temperature seasonality). It has been demonstrated that macrofungal fruiting assemblages are correlated with the thermal environment at a European scale. However, whether macrofungal communities also display phylogenetic structuring along with mean and seasonal temperature gradients is currently unknown. Here, we used a mega-phylogeny and 2,882 macrofungal fruiting species distributions across Europe and asked whether: (i) assemblages at the end of the mean (warm and cold) and seasonal (continental) gradient are phylogenetically more similar than expected (phylogenetic alpha diversity); (ii) assemblages subjected to different mean and seasonal temperature conditions consist of different related lineages (phylogenetic beta diversity). Phylogenetic alpha diversity analysis revealed that assemblages were phylogenetically clustered in warm and cold environments, indicating that phylogenetically related species sharing similar traits are favoured in the more extreme environments. In contrast, assemblages were phylogenetically more overdispersed in temperature seasonal (continental) environments, indicating limiting similarity. Phylogenetic beta diversity was significantly correlated with mean and seasonality temperature differences, a response mainly driven by a few exclusive genera. Our results show that macrofungal assemblages are phylogenetically structured by temperature across Europe, suggesting phylogenetically constrained specialization towards temperature extremes. Climate warming might thus lead to the selection of warm-tolerant and the expulsion of cold-adapted species with a wide range of ecological consequences.