What do Pneumocystis organisms tell us about the phylogeography of their hosts? The case of the woodmouse Apodemus sylvaticus in continental Europe and western Mediterranean islands.

Christine Demanche,Véronique Barriel,Claire Pinçon,Eric Viscogliosi,El Moukhtar Aliouat,Serge Morand,Muriel Pottier,Manjula Deville,Johan Michaux,Cécile Marie Aliouat-Denis,Eduardo Dei-Cas,Christophe Noël,Jacques Guillot

doi:10.1371/journal.pone.0120839

Abstract

Pneumocystis fungi represent a highly diversified biological group with numerous species, which display a strong host-specificity suggesting a long co-speciation process. In the present study, the presence and genetic diversity of Pneumocystis organisms was investigated in 203 lung samples from woodmice (Apodemus sylvaticus) collected on western continental Europe and Mediterranean islands. The presence of Pneumocystis DNA was assessed by nested PCR at both large and small mitochondrial subunit (mtLSU and mtSSU) rRNA loci. Direct sequencing of nested PCR products demonstrated a very high variability among woodmouse-derived Pneumocystis organisms with a total number of 30 distinct combined mtLSU and mtSSU sequence types. However, the genetic divergence among these sequence types was very low (up to 3.87%) and the presence of several Pneumocystis species within Apodemus sylvaticus was considered unlikely. The analysis of the genetic structure of woodmouse-derived Pneumocystis revealed two distinct groups. The first one comprised Pneumocystis from woodmice collected in continental Spain, France and Balearic islands. The second one included Pneumocystis from woodmice collected in continental Italy, Corsica and Sicily. These two genetic groups were in accordance with the two lineages currently described within the host species Apodemus sylvaticus. Pneumocystis organisms are emerging as powerful tools for phylogeographic studies in mammals.

Highlights

Phylogeography is a field of research, which studies the principles and processes determining the geographical distribution of genetic lineages
A sample was considered to be positive for the presence of Pneumocystis DNA when a specific band was amplified by PCR at the expected size either at the mitochondrial large subunit (mtLSU) or mitochondrial small subunit (mtSSU) rRNA locus or at both loci (Table 1)
Pneumocystis DNA was detected in 189 out of 203 woodmice lung samples examined (93.1%). Amplifications at both mtSSU and mtLSU rDNA were positive for the same individual in 38 animals (Table 1)

Summary

Introduction

Phylogeography is a field of research, which studies the principles and processes determining the geographical distribution of genetic lineages. Parasites provide an additional source of information and can better reconstruct the common history of hosts and parasites [1]. For this reason, some parasites have been recently used as phylogeographic markers [1,2,3,4,5,6,7]. Studies on the co-divergence between A. sylvaticus and the parasitic nematode Heligmosomoides polygyrus [2, 8] demonstrated a general association between the parasite genetic structure and the host evolutionary history

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