Phylogenetic congruence between subtropical trees and their associated fungi.

Xubing Liu,Shixiao Yu,Minxia Liang,Gregory S Gilbert,Rampal S Etienne

doi:10.1002/ece3.2503

Abstract

Recent studies have detected phylogenetic signals in pathogen–host networks for both soil‐borne and leaf‐infecting fungi, suggesting that pathogenic fungi may track or coevolve with their preferred hosts. However, a phylogenetically concordant relationship between multiple hosts and multiple fungi in has rarely been investigated. Using next‐generation high‐throughput DNA sequencing techniques, we analyzed fungal taxa associated with diseased leaves, rotten seeds, and infected seedlings of subtropical trees. We compared the topologies of the phylogenetic trees of the soil and foliar fungi based on the internal transcribed spacer (ITS) region with the phylogeny of host tree species based on matK, rbcL, atpB, and 5.8S genes. We identified 37 foliar and 103 soil pathogenic fungi belonging to the Ascomycota and Basidiomycota phyla and detected significantly nonrandom host–fungus combinations, which clustered on both the fungus phylogeny and the host phylogeny. The explicit evidence of congruent phylogenies between tree hosts and their potential fungal pathogens suggests either diffuse coevolution among the plant–fungal interaction networks or that the distribution of fungal species tracked spatially associated hosts with phylogenetically conserved traits and habitat preferences. Phylogenetic conservatism in plant–fungal interactions within a local community promotes host and parasite specificity, which is integral to the important role of fungi in promoting species coexistence and maintaining biodiversity of forest communities.

Highlights

Ecologists have proposed many mechanisms to explain the extraordinarily high diversity in the tropics
The high diversity of fungi living in plant tissue and soils (Hawksworth, 2012) provides a large pool of potential enemies, but many plant-associated fungi can infect multiple hosts and individual plant hosts can be coinfected by multiple fungi (Barrett, Kniskern, Bodenhausen, Zhang, & Bergelson, 2009; Gilbert & Webb, 2007; Hersh, Vilgalys, & Clark, 2012)
Multihost fungi vary in host specificity and ecological function depending on both host and environmental condition (Hersh et al, 2012), which makes it difficult to evaluate the impacts of many possible combinations of fungi

Summary

| INTRODUCTION

Ecologists have proposed many mechanisms to explain the extraordinarily high diversity in the tropics. We evaluated the negative plant–soil feedbacks mediated by soil biota, and documented a gradual increase in seedling survival with phylogenetic distance between tree species (Liu et al, 2012) as well as genetic distance among conspecific individuals (Liu, Etienne, Liang, Wang, & Yu, 2015). All these studies suggest phylogenetically conservative feedback between hosts and plant-associated fungi, but the nonrandom association has not been measured directly nor examined in the framework of a network of interacting sets of plant and pathogen species. Because most pathogens can attack multiple hosts but their host ranges are constrained by phylogenetically conserved traits that reflect evolutionary relationships important in plant–fungal interactions, we expect to find closely related hosts linked by shared pathogens and closely related pathogens using similar sets of host species

| MATERIALS AND METHODS

Findings

| DISCUSSION