Soil nematode abundance and diversity from four vegetation types in Central Mexico

Abstract

Soil nematode abundance and MOTU diversity were estimated from a geographically broad area of Mexico that included four out of seven recognised vegetation types. Vegetation types were assessed for abundance and diversity of nematode communities and inferred ecological relationships between them. Soils were sampled from tropical rainforest, tropical dry deciduous forest, temperate coniferous forest and xerophytic shrub during 2013, 2014 and 2015. Fourteen sampling sites withca10-20 samples per site from 11 localities spread across Central Mexico were assessed. Altitudes sampled ranged from 113 m a.s.l. (tropical coastal plain) to 2400 m a.s.l. (Trans-Mexican Volcanic Belt). Samples were drawn from conserved and cultivated plots from each sampling site covering an area of ⩾100 m2. A total of 13 263 individuals from 25 identified families of nematodes were collected. Family abundance and complementarity indices between sites revealed to some extent the affinities between vegetation types. Nevertheless, statistical analyses revealed no differences between nematode family abundances between sites, only between families across all sites. Molecular operational taxonomic units (MOTU) methods were employed as a framework to assess biodiversity. From these, 77 high-quality sequences for taxonomic barcoding were recovered and later identified with morphological traits. Only six sequences matched at a 98-99% level with those reported in GenBank. Sequences amounted to a total of 41 MOTU, where 100% of the MOTU from both conserved and disturbed tropical rainforest, tropical dry deciduous forest and xerophytic shrub exhibited a ⩾3% cut-off genetic identity, whilst temperate coniferous forest and disturbed temperate coniferous forest showed 73% and 70% respectively. In addition, 12.2% MOTU were shared among localities and 87.8% exhibited an apparently locality-limited distribution. The potential for a considerable diversity of nematodes, as revealed from a small sample of MOTU diversity, is discussed.