Biological invasions increase the richness of arbuscular mycorrhizal fungi from a Hawaiian subtropical ecosystem

Abstract

Biological invasions can have various impacts on the diversity of important microbial mutualists such as mycorrhizal fungi, but few studies have tested whether the effects of invasions on mycorrhizal diversity are consistent across spatial gradients. Furthermore, few of these studies have taken place in tropical ecosystems that experience an inordinate rate of invasions into native habitats. Here, we examined the effects of plant invasions dominated by non-native tree species on the diversity of arbuscular mycorrhizal (AM) fungi in Hawaii. To test the hypothesis that invasions result in consistent changes in AM fungal diversity across spatial gradients relative to native forest habitats, we sampled soil in paired native and invaded sites from three watersheds and used amplicon sequencing to characterize AM fungal communities. Whether our analyses considered phylogenetic relatedness or not, we found that invasions consistently increased the richness of AM fungi.However, AM fungal species composition was not related to invasion status of the vegetation nor local environment, but stratified by watershed. Our results suggest that while invasions can lead to an overall increase in the diversity of microbial mutualists, the effects of plant host identity or geographic structuring potentially outweigh those of invasive species in determining the community membership of AM fungi. Thus, host specificity and spatial factors such as dispersal need to be taken into consideration when examining the effects of biological invasions on symbiotic microbes.

Invasive alien plant species: Their impact on environment, ecosystem services and human health

“…It is well known that mutualistic microbial diversity of arbuscular mycorrhizal fungi (AMF) remarkably assists in the sustenance of forests. Recently, a few IAPS have been reported to promote the diversity of AMF in Hawaii forests (Gomes et al, 2018). Further, it has been observed that certain IAPS (Centaurea stoebe and Euphorbia esula) increased the abundance as well as diversity of mycorrhizal fungi, which have immense role in ecosystem functioning (Lekberg et al, 2013).…”

Biological invasions alter environmental microbiomes: A meta-analysis

“…[ 25 ], and Vincetoxicum rossicum [ 26 ] did not alter the structure of soil microbial communities. Also, some microcosms exposed to the simultaneous invasion of multiple plant species [ 27 – 29 ] did not alter soil microbiomes. Similarly, soil microbiome structure in microcosms did not change with the addition of the invasive earthworm Aporrectodea trapezoides [ 30 ].…”

Biological invasions alter environmental microbiomes: a meta-analysis

“…While several studies have investigated the effects of species invasions on environmental microbiomes, we still lack a generalized consensus across different environmental microbiomes and systems. Previous studies have found that invasive species increased environmental microbial diversity [13,19], while others reported a decrease [15,20,29]. However, the majority of studies did not analyze the microbial diversity, as they used techniques that did not allow for such analysis, or reported no changes [9,10,23–28,30,11,12,14,16–18,21,22].…”

“…[25], and Vincetoxicum rossicum [26] did not alter the structure of soil microbial communities. Also, some microcosms exposed to the simultaneous invasion of multiple plant species [27–29] did not alter soil microbiomes. Similarly, soil microbiome structure in microcosms did not change with the addition of the invasive earthworm Aporrectodea trapezoides [30].…”

“…DGGE, PLFA, t-RFLP) that limit fine scale investigations of biological invasions on environmental microbiome diversity and taxonomical composition. Among the studies using high-throughput amplicon-sequencing techniques, most did not find changes in microbiome diversity [12,14,17,18,21,25,27,28,30], few reported a decrease of microbial diversity in response to invasion [15,20,29], and fewer still reported an increase [13,19]. Thus, there is still little consensus on the effects of biological invasions on the diversity and taxonomical structure of the environmental microbiomes, both tied to the stability and function of microbial communities [31,32].…”