Species composition of arbuscular mycorrhizal communities changes with elevation in the Andes of South Ecuador.

Ingeborg Haug,Sabrina Setaro,Juan Pablo Suárez,Erika Kothe

doi:10.1371/journal.pone.0221091

Abstract

Arbuscular mycorrhizal fungi (AMF) are the most prominent mycobionts of plants in the tropics, yet little is known about their diversity, species compositions and factors driving AMF distribution patterns. To investigate whether elevation and associated vegetation type affect species composition, we sampled 646 mycorrhizal samples in locations between 1000 and 4000 m above sea level (masl) in the South of Ecuador. We estimated diversity, distribution and species compositions of AMF by cloning and Sanger sequencing the 18S rDNA (the section between AML1 and AML2) and subsequent derivation of fungal OTUs based on 99% sequence similarity. In addition, we analyzed the phylogenetic structure of the sites by computing the mean pairwise distance (MPD) and the mean nearest taxon difference (MNTD) for each elevation level. It revealed that AMF species compositions at 1000 and 2000 masl differ from 3000 and 4000 masl. Lower elevations (1000 and 2000 masl) were dominated by members of Glomeraceae, whereas Acaulosporaceae were more abundant in higher elevations (3000 and 4000 masl). Ordination of OTUs with respect to study sites revealed a correlation to elevation with a continuous turnover of species from lower to higher elevations. Most of the abundant OTUs are not endemic to South Ecuador. We also found a high proportion of rare OTUs at all elevations: 79–85% of OTUs occurred in less than 5% of the samples. Phylogenetic community analysis indicated clustering and evenness for most elevation levels indicating that both, stochastic processes and habitat filtering are driving factors of AMF community compositions.

Highlights

Arbuscular mycorrhizal fungi (AMF) are the most prominent mycobionts of plants in the Neotropics [1, 2]
Knowledge of this mutualistic plant-fungus association is indispensable for understanding the biology and ecology of tropical ecosystems
The 1000 m sites are located in the Bombuscaro area in Parque Nacional Podocarpus (4 ̊11’S, ̊96’W); the 2000 m sites in the Reserva Biologica San Francisco (RBSF; 3 ̊58’S, ̊04’W) on the eastern slope of the Cordillera El Consuelo, Zamora-Chinchipe Province; the 3000 m sites in Cajanuma area (4 ̊12’S, 79 ̊17’W) in Parque Nacional Podocarpus and in the Nero area (2 ̊95’S, 79 ̊10’W) at Parque Nacional Cajas; and the 4000 m sites in Tutupali (3 ̊03’S, 79 ̊15’W), Soldados (2 ̊98’S, 79 ̊31’W) and the Toreadora area (2 ̊47’S, 79 ̊11’W) at Parque Nacional Cajas (Fig 1)

Summary

Introduction

Arbuscular mycorrhizal fungi (AMF) are the most prominent mycobionts of plants in the Neotropics [1, 2]. Arbuscular mycorrhizal fungi belong to the phylum Glomeromycotina, and are crucial for providing minerals to the vast majority of plants including most tree species in nutrient-poor environments [1, 2]. Knowledge of this mutualistic plant-fungus association is indispensable for understanding the biology and ecology of tropical ecosystems.

Objectives

Methods

Results