Over the hills, but how far away? Estimates of mushroom geographic range extents

Abstract

Aim Geographic distributions of mushroom species remain poorly understood despite their importance for advancing our understanding of the habitat requirements, species interactions and ecosystem functions of this key group of organisms. Here, we estimate geographic range extents (maximum within‐species geographic distance) of genetically defined operational taxonomic units (OTUs). Location World‐wide, with emphasis on the American Pacific Northwest. Taxa Amanita, Agaricus, Cortinarius, Galerina, Hebeloma, Hydnum, Hygrocybe, Hygrophorus, Inocybe, Lepiota, Pholiota, and Russula + Lactarius; other genera in Agaricomycotina. Method We used publicly available OTUs from ribosomal internal transcribed spacer (ITS) sequences (n = 15,373) from 12 mushroom genera with worldwide distributions. For each of 2,324 ~ species‐level OTUs, we estimated the maximum within‐species range extent based on sample locality records. In parallel, we estimated range extents for species in four tree genera. Contrasting estimates from well‐studied trees allowed us to test for potential biases in our range estimates of less well inventoried mushrooms. Results The median range extents across the 2,324 mushroom OTUs varied from ~ 1,200 to 4,039 km, depending on assumptions. These extents were significantly lower than estimates from permuted or randomized data. Mushroom ranges were comparable to the median natural range extent of tree species (1,613 km). In contrast, the tree median species range increased to 16,581 km when anthropogenic range extensions were included. At least 10 mushroom species were similarly broadly distributed, eight of which have been associated with human activity. Main conclusions Overall, like tree species, mycorrhizal and saprotrophic fungi show evidence of biogeographic structure rather than global distributions. This reconstruction of geographic range extents drew upon investments into ITS barcoding of extensive herbarium collections. Large scale analyses such as ours can yield estimates of fungal geographic range extents that are a prerequisite to a deeper understanding of the diverse roles of fungi in ecosystems.

Fungal community turnover along steep environmental gradients from geothermal soils in Yellowstone National Park

“…Additionally, the number of saprotrophic OTUs significantly changed with distance from the creek shore, with an uptick at an intermediate distance while there was no difference found in EM fungi. Interestingly, mycorrhizal fungi have been predicted to display more restricted ranges compared to saprotrophs [68], although global empirical data failed to recover this pattern [69]. This would lead to a prediction of edaphic factors affecting mycorrhizal fungi disproportionately, which is the opposite of what we found.…”

Systematic analysis ofRussulain the North American Rocky Mountain alpine zone

“…Therefore, large intercontinental distributions appear to be a trend in Arctic and alpine ectomycorrhizal genera and implies that species maintain large, intercontinental populations. This is in contrast with data from other habitats that show most ectomycorrhizal fungi have small geographic distributions (Bazzicalupo et al 2019) and that spore dispersal from basidiocarps appears limited (Fischer et al 2010). Although we do not have data to explain the large, intercontinental distributions found here for alpine species of Russula in the Rocky Mountains, we believe that one of the most parsimonious explanation is that Arctic and alpine fungi are following their primary host, dwarf and shrubby species of Salix.…”

“…Another study analyzed DNA from sporocarps and soil samples to determine that Russula was the fifth most species-rich genus in Svalbard (Geml et al 2012). They proposed that long-distance, transoceanic dispersal occurs in Arctic fungi, in contrast to the more limited dispersal of temperate Russula species (Bazzicalupo et al 2019). As molecular tools became easier to use and more reliable, researchers began to sort out and clarify certain groups of Russula.…”

“…Therefore, we hypothesize that the Russula species that occur in the Rocky Mountain alpine will have large intercontinental distributions. Long distance, transoceanic dispersal has been hypothesized to explain minimal molecular differences in Arctic species of ectomycorrhizal fungi (Geml et al 2012), in contrast to the more limited dispersal of temperate Russula species (Bazzicalupo et al 2019). However, long distance dispersal is a problematic explanation for fungal distributions in disjunct alpine areas.…”

The Limited Establishment of Native Ectomycorrhizal Fungi in Exotic Eucalyptus spp. Stands in Japan

“…The aforementioned study demonstrated that most ECM fungi could only be distributed in regions with ECM plant taxa that are similar to those on Yakushima Island, implying that the distribution ranges of ECM fungi are restricted by host specificity rather than by climate preference and dispersal limitations. Since the global distribution of ECM fungi has been rarely investigated ( Sato et al, 2012 ; Tedersoo et al, 2014 ; García-Guzmán et al, 2017 ; Bazzicalupo et al, 2018 ), further studies are required to elucidate the influence of host specificity on the distribution ranges of ECM fungi.…”