Changes in richness and community composition of ectomycorrhizal fungi among altitudinal vegetation types on Mount Kinabalu in Borneo

Abstract

The distribution patterns of tropical ectomycorrhizal (ECM) fungi along altitudinal gradients remain largely unknown. Furthermore, despite being an iconic site for biodiversity research, virtually nothing is known about the diversity and spatial patterns of fungi on Mt Kinabalu and neighbouring mountain ranges. We carried out deep DNA sequencing of soil samples collected between 425 and 4000 m above sea level to compare richness and community composition of ECM fungi among altitudinal forest types in Borneo. In addition, we tested whether the observed patterns are driven by habitat or by geometric effect of overlapping ranges of species (mid-domain effect). Community composition of ECM fungi was strongly correlated with elevation. In most genera, richness peaked in the mid-elevation montane forest zone, with the exception of tomentelloid fungi, which showed monotonal decrease in richness with increasing altitude. Richness in lower-mid- and mid-elevations was significantly greater than predicted under the mid-domain effect model. We provide the first insight into the composition of ECM fungal communities and their strong altitudinal turnover in Borneo. The high richness and restricted distribution of many ECM fungi in the montane forests suggest that mid-elevation peak richness is primarily driven by environmental characteristics of this habitat and not by the mid-domain effect.

Microbes follow Humboldt: temperature drives plant and soil microbial diversity patterns from the Amazon to the Andes

“…Consistent with this idea, correlations between plant and fungal β‐diversity alongside high variation in α‐diversity patterns among specific fungal phyla (especially those that form plant associations) have been observed across elevation gradients in a range of ecosystems (Geml et al. , , Merckx et al. , Looby et al.…”

“…) and opposing α‐diversity patterns have been observed for arbuscular mycorrhizal (AM) and EM fungi (Geml et al. , Kivlin et al. ).…”

“…The majority of fungal diversity studies on mountain gradients have focused on specific phyla, reporting high variation in α‐diversity patterns (Geml et al. , , Merckx et al. , Geml ) and strong associations with plant–host distributions such as with AM‐ and EM‐fungal‐associated communities (Kivlin et al.…”

Ectomycorrhizal associations in the tropics – biogeography, diversity patterns and ecosystem roles

“…Nonetheless, Geml et al . () found peak ECM fungal richness in mid‐elevation forests on Mt. Kinabalu, Borneo, even though ECM host density was putatively similar over a broader elevation gradient.…”

Soil Biology Research across Latitude, Elevation and Disturbance Gradients: A Review of Forest Studies from Puerto Rico during the Past 25 Years

“…The study of phylogenetic origins of endemic species of plants, animals and fungi on a young mountain in Malaysia by Merckx et al [52] showed strong niche conservatism that results in high species turnover along the elevation gradient [55,56]. A subsequent analysis by Geml et al [57] from the same mountain showed that the peak in species richness of ectomycorrhizal fungi at lower-middle elevation was primarily tied to narrow environmental niches and not the result of broad-range species overlapping in the middle of the gradient (known as the mid-domain effect). Sensitivities of tropical montane organisms to changes in environmental factors is important in the context of climate change [18,19,51,58], but not all changes in biota are direct responses to environment [51].…”