Soil nematodes show a mid-elevation diversity maximum and elevational zonation on Mt. Norikura, Japan

Abstract

Little is known about how nematode ecology differs across elevational gradients. We investigated the soil nematode community along a ~2,200 m elevational range on Mt. Norikura, Japan, by sequencing the 18S rRNA gene. As with many other groups of organisms, nematode diversity showed a high correlation with elevation, and a maximum in mid-elevations. While elevation itself, in the context of the mid domain effect, could predict the observed unimodal pattern of soil nematode communities along the elevational gradient, mean annual temperature and soil total nitrogen concentration were the best predictors of diversity. We also found nematode community composition showed strong elevational zonation, indicating that a high degree of ecological specialization that may exist in nematodes in relation to elevation-related environmental gradients and certain nematode OTUs had ranges extending across all elevations, and these generalized OTUs made up a greater proportion of the community at high elevations – such that high elevation nematode OTUs had broader elevational ranges on average, providing an example consistent to Rapoport’s elevational hypothesis. This study reveals the potential for using sequencing methods to investigate elevational gradients of small soil organisms, providing a method for rapid investigation of patterns without specialized knowledge in taxonomic identification.

Taxonomic profiling of individual nematodes isolated from copse soils using deep amplicon sequencing of four distinct regions of the 18S ribosomal RNA gene

“…Region 1 covered both V1 and V2 hypervariable regions, and region 2 spanned the V4 regions of the eukaryotic 18S rDNA sequences reported by Hugerth et al [38]. Both PCR target regions have been used in previous DNA barcode analyses of nematode communities using the next-generation sequencer Roche 454 [20,21,26,39] or Illumina MiSeq [22,23,25,27,28,40,41]. Regions 2 and 3 were newly examined in this study and spanned the V4 region and the V5-V7 regions, respectively ( Fig 1B).…”

“…In the past decade, the extensive advancement of DNA sequencing technology has transformed from the "one-by-one DNA barcoding" method using Sanger sequencing of a PCR amplicon from an individual organism, to the "DNA metabarcoding" method using NGS-assisted massive sequencing of an amplicon from a complex community. Currently, several studies concerning the DNA metabarcoding of terrestrial [20][21][22][23][24][25] and marine nematodes [26][27][28] have been conducted using deep sequencing of SSU-derived amplicons. However, potential regions of the SSU gene that would be most suitable for NGS-based DNA metabarcoding have not been investigated in detail yet.…”

Fungal Elevational Rapoport pattern from a High Mountain in Japan

“…Norikura, Dong et al . 32 found an elevational RE pattern in soil nematodes. None of the previously published studies on elevational trends in fungal subgroups has covered the subject of RE.…”

Contrasting responses of above- and below-ground herbivore communities along elevation

“…Herbivore nematodes are capable of substantial uptakes of plant root biomass (Ingham and Detling 1990 ; Hodda et al 2009 ) and are distinguished into functional feeding groups including five plant root-feeding strategies (sedentary endoparasites, migratory endoparasites, semi-endoparasites, ectoparasites, and epidermal cells and root-hair feeders; Yeates et al 1993 ). Responses of herbivore nematodes to elevation have seldom been described with reports of decrease (Dong et al 2017 ) or increase (Kergunteuil et al 2016 ) in taxonomic richness and abundance at a higher elevation. To date, concomitant investigations of both orthoptera and nematode communities, their functional responses and those of local plant communities along elevation, are still lacking.…”