Incorporating phylogenetic information into studies of beta diversity allows ecologists to identify the degree to which shared evolutionary histories of species explain ecological patterns observed today. When combined with taxonomic beta diversity, environmental gradient analyses can provide a deeper mechanistic understanding of the current patterns of biological diversity. For example, these analyses can quantify whether species turn-over along environmental gradients is characterized by closely related species occupying similar niches. Such relationships have only recently been investigated in plants, but there have been no comparable studies of fungi, despite their tremendous species richness and important roles in ecosystem processes. In this study we use a uniquely comprehensive dataset, assembled from citizen science and fungaria from nine countries, to explore the taxonomic and phylogenetic beta diversity of macrofungi across Europe. We used Soerensen index to quantify taxonomic similarity and the phylosor index as an analogous measure of phylogenetic beta diversity (paired sets of tips on a phylogeny). We were particularly interested to test how beta diversity is related to environmental distances (e.g. mean annual temperature) and whether the strength of this relationship has been altered by climate change. For this purpose we conducted separate analyses for the time periods 1970-1990 and 1991-2010.
Results showed similar increases in both phylogenetic and taxonomic dissimilarity with larger differences in temperature. We found independent effects of temperature differences when correcting for geographical distances. Moreover, we found that the slope of the observed relationship between beta diversity and differences in temperature is steeper for the time interval 1991-2010 compared to the interval 1970-1990. These results suggest that turnover in fungal communities across Europe is related to climate, and that climate change may already be affecting taxonomic and phylogenetic beta diversity. These changes in patterns of fungal diversity could have profound implications for the many ecosystem processes regulated by fungi.