Imprints of latitude, host taxon, and decay stage on fungus‐associated arthropod communities

Abstract

Interactions among fungi and insects involve hundreds of thousands of species. While insect communities on plants have formed some of the classic model systems in ecology, fungus-based communities and the forces structuring them remain poorly studied by comparison. We characterize the arthropod communities associated with fruiting bodies of eight mycorrhizal basidiomycete fungus species from three different orders along a 1200-km latitudinal gradient in northern Europe. We hypothesized that, matching the pattern seen for most insect taxa on plants, we would observe a general decrease in fungalassociated species with latitude. Against this backdrop, we expected local communities to be structured by host identity and phylogeny, with more closely related fungal species sharing more similar communities of associated organisms. As a more unique dimension added by the ephemeral nature of fungal fruiting bodies, we expected further imprints generated by successional change, with younger fruiting bodies harboring communities different from older ones. Using DNA metabarcoding to identify arthropod communities from fungal fruiting bodies, we found that latitude left a clear imprint on fungusassociated arthropod community composition, with host phylogeny and decay stage of fruiting bodies leaving lesser but still-detectable effects. The main latitudinal imprint was on a high arthropod species turnover, with no detectable pattern in overall species richness. Overall, these findings paint a new picture of the drivers of fungus-associated arthropod communities, suggesting that latitude will not affect how many arthropod species inhabit a fruiting body but, rather, what species will occur in it and at what relative abundances (as measured by sequence read counts). These patterns upset simplistic predictions regarding latitudinal gradients in species richness and in the strength of biotic interactions.

Environmental responses of fruiting fungal communities are phylogenetically structured

“…While arthropods feeding on fungal fruiting bodies are rarely specialized on particular host species, many fungivores feed on sets of related fungal hosts (Orledge and Reynolds 2005, Põldmaa et al 2016, Koskinen et al 2019. Such cladelevel specificity was also revealed by Koskinen et al (2022), who found the overall similarity of arthropod communities to decrease with an increasing phylogenetic distance among fungal hosts. For consumers specializing on particular fungal taxa or clades, non-random responses of entire fungal clades to spatiotemporal variation in environmental conditions will therefore introduce further unpredictability in resource availability: not only are fruiting bodies as such short-lived and patchily distributed, but the occurrence and abundance of entire host groups is further clumped in time and space.…”

“…One type of communities on which phylogenetic signatures remain poorly known (Abrego et al 2022, Bässler et al 2022) are local assemblages of fungal fruiting bodies. This constitutes an important knowledge gap because fungal fruiting bodies provide a resource for a plethora of organisms (Hanski 1989, Osawa et al 2011, Kurina et al 2015, Koskinen et al 2019, 2022). Fungus‐based trophic networks are highly diverse even in the boreal and temperate zones, where thousands of fungal species produce macroscopic fruiting bodies (Salo et al 2005, Mueller et al 2007).…”

“…How the local composition and abundance of fungal fruiting bodies affect the associated communities of other taxa is an area of vigorous research (Põldmaa et al 2016, Koskinen et al 2019, 2022). Despite their apparent ubiquity, fungal fruiting bodies will namely constitute a spatially and temporally unpredictable resource for fungivorous vertebrates and invertebrates (Butterworth et al 2023).…”

“…Theoretically, unpredictable abundance of individual host species favors generalism as a bet‐hedging strategy in consumers (Hanski 1989, Poisot et al 2011). Indeed, many arthropods associated with fruiting bodies of forest fungi show low levels of specialization, or tend to be specialized at the level of host genus rather than species (Ståhls et al 1989, Thorn et al 2015, Põldmaa et al 2016, Koskinen et al 2019, 2022). In fungivores associated with particular fungal taxa, the specialization tends to target specific features in host ecology or morphology (Orledge and Reynolds 2005, Põldmaa et al 2015, Lunde et al 2022).…”

Mycophagy: A Global Review of Interactions between Invertebrates and Fungi

“…As technology advances, researchers can utilize new cost-effective and efficient ways to identify invertebrates in sporocarps. The shift away from traditional rearing techniques to DNA metabarcoding will enhance our understanding and give us new insights into this subfield [ 104 , 105 , 106 , 107 , 108 , 109 ].…”