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Population genetics and phylogenetic inference in bacterial molecular systematics: the roles of migration and recombination in Bradyrhizobium species cohesion and delineation.

Abstract：

:A combination of population genetics and phylogenetic inference methods was used to delineate Bradyrhizobium species and to uncover the evolutionary forces acting at the population-species interface of this bacterial genus. Maximum-likelihood gene trees for atpD, glnII, recA, and nifH loci were estimated for diverse strains from all but one of the named Bradyrhizobium species, and three unnamed "genospecies," including photosynthetic isolates. Topological congruence and split decomposition analyses of the three housekeeping loci are consistent with a model of frequent homologous recombination within but not across lineages, whereas strong evidence was found for the consistent lateral gene transfer across lineages of the symbiotic (auxiliary) nifH locus, which grouped strains according to their hosts and not by their species assignation. A well resolved Bayesian species phylogeny was estimated from partially congruent glnII+recA sequences, which is highly consistent with the actual taxonomic scheme of the genus. Population-level analyses of isolates from endemic Canarian genistoid legumes based on REP-PCR genomic fingerprints, allozyme and DNA polymorphism analyses revealed a non-clonal and slightly epidemic population structure for B. canariense isolates of Canarian and Moroccan origin, uncovered recombination and migration as significant evolutionary forces providing the species with internal cohesiveness, and demonstrated its significant genetic differentiation from B. japonicum, its sister species, despite their sympatry and partially overlapped ecological niches. This finding provides strong evidence for the existence of well delineated species in the bacterial world. The results and approaches used herein are discussed in the context of bacterial species concepts and the evolutionary ecology of (brady)rhizobia.

journal_name

Mol Phylogenet Evol

journal_title

Molecular phylogenetics and evolution

authors

Vinuesa P,Silva C,Werner D,Martínez-Romero E

doi

10.1016/j.ympev.2004.08.020

keywords:

subject

Has Abstract

pub_date

2005-01-01 00:00:00

pages

29-54

issue

eissn

1055-7903

issn

1095-9513

pii

S1055-7903(04)00276-3

journal_volume

pub_type

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Population genetics and phylogenetic inference in bacterial molecular systematics: the roles of migration and recombination in Bradyrhizobium species cohesion and delineation.