Scholars@Duke
Jennifer Jo Wernegreen

Jennifer Jo Wernegreen

Associate Professor of Environmental and Evolutionary Genomics in the Division of Environmental Sciences and Policy
Environmental Sciences and Policy
j.wernegreen@duke.edu
3102 Grainger Hall, Duke University, Durham, NC 27708
3102 Grainger Hall, Duke Univ., 9 Circuit Drive, Durham, NC 27708
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Selected Publications

Genomic erosion and extensive horizontal gene transfer in gut-associated Acetobacteraceae.

Journal Article BMC genomics · June 2019 BackgroundSymbiotic relationships between animals and bacteria have profound impacts on the evolutionary trajectories of each partner. Animals and gut bacteria engage in a variety of relationships, occasionally persisting over evolutionary timesca ... Full text Cite

In it for the long haul: evolutionary consequences of persistent endosymbiosis.

Journal Article Current opinion in genetics & development · December 2017 Phylogenetically independent bacterial lineages have undergone a profound lifestyle shift: from a free-living to obligately host-associated existence. Among these lineages, intracellular bacterial mutualists of insects are among the most intimate, constrai ... Full text Cite

Ancient bacterial endosymbionts of insects: Genomes as sources of insight and springboards for inquiry.

Journal Article Experimental cell research · September 2017 Ancient associations between insects and bacteria provide models to study intimate host-microbe interactions. Currently, a wealth of genome sequence data for long-term, obligately intracellular (primary) endosymbionts of insects reveals profound genomic co ... Full text Cite

Deep divergence and rapid evolutionary rates in gut-associated Acetobacteraceae of ants.

Journal Article BMC microbiology · July 2016 BackgroundSymbiotic associations between gut microbiota and their animal hosts shape the evolutionary trajectories of both partners. The genomic consequences of these relationships are significantly influenced by a variety of factors, including ni ... Full text Cite

Endosymbiont evolution: predictions from theory and surprises from genomes.

Journal Article Annals of the New York Academy of Sciences · December 2015 Genome data have created new opportunities to untangle evolutionary processes shaping microbial variation. Among bacteria, long-term mutualists of insects represent the smallest and (typically) most AT-rich genomes. Evolutionary theory provides a context t ... Full text Cite

Thermally adaptive tradeoffs in closely related marine bacterial strains.

Journal Article Environ Microbiol · July 2015 Time series studies have shown that some bacterial taxa occur only at specific times of the year while others are ubiquitous in spite of seasonal shifts in environmental variables. Here, we ask if these ubiquitous clades are generalists that grow over a wi ... Full text Link to item Cite

Genome evolution in an ancient bacteria-ant symbiosis: parallel gene loss among Blochmannia spanning the origin of the ant tribe Camponotini.

Journal Article PeerJ · January 2015 Stable associations between bacterial endosymbionts and insect hosts provide opportunities to explore genome evolution in the context of established mutualisms and assess the roles of selection and genetic drift across host lineages and habitats. Blochmann ... Full text Cite

Can't take the heat: high temperature depletes bacterial endosymbionts of ants.

Journal Article Microbial ecology · October 2013 Members of the ant tribe Camponotini have coevolved with Blochmannia, an obligate intracellular bacterial mutualist. This endosymbiont lives within host bacteriocyte cells that line the ant midgut, undergoes maternal transmission from host queens to offspr ... Full text Cite

First impressions in a glowing host-microbe partnership.

Journal Article Cell host & microbe · August 2013 Despite the clear significance of beneficial animal-microbe associations, mechanisms underlying their initiation and establishment are rarely understood. In this issue of Cell Host & Microbe, Kremer et al. (2013) reveal that first contact within the squid- ... Full text Cite

Animals in a bacterial world, a new imperative for the life sciences.

Journal Article Proc Natl Acad Sci U S A · February 26, 2013 In the last two decades, the widespread application of genetic and genomic approaches has revealed a bacterial world astonishing in its ubiquity and diversity. This review examines how a growing knowledge of the vast range of animal-bacterial interactions, ... Full text Link to item Cite

Proteomic analysis of an unculturable bacterial endosymbiont (Blochmannia) reveals high abundance of chaperonins and biosynthetic enzymes.

Journal Article J Proteome Res · February 1, 2013 Many insect groups have coevolved with bacterial endosymbionts that live within specialized host cells. As a salient example, ants in the tribe Camponotini rely on Blochmannia, an intracellular bacterial mutualist that synthesizes amino acids and recycles ... Full text Link to item Cite

Sequence context of indel mutations and their effect on protein evolution in a bacterial endosymbiont.

Journal Article Genome biology and evolution · January 2013 Indel mutations play key roles in genome and protein evolution, yet we lack a comprehensive understanding of how indels impact evolutionary processes. Genome-wide analyses enabled by next-generation sequencing can clarify the context and effect of indels, ... Full text Cite

Strategies of genomic integration within insect-bacterial mutualisms.

Journal Article The Biological bulletin · August 2012 Insects, the most diverse group of macroorganisms with 900,000 known species, have been a rich playground for the evolution of symbiotic associations. Symbionts of this enormous animal group include a range of microbial partners. Insects are prone to estab ... Full text Cite

Endosymbiosis.

Journal Article Current biology : CB · July 2012 The phenomenon of endosymbiosis, or one organism living within another, has deeply impacted the evolution of life and continues to shape the ecology of countless species. Traditionally, biologists have viewed evolution as a largely bifurcating pattern, ref ... Full text Cite

Mutualism meltdown in insects: bacteria constrain thermal adaptation.

Journal Article Current opinion in microbiology · June 2012 Predicting whether and how organisms will successfully cope with climate change presents critical questions for biologists and environmental scientists. Models require knowing how organisms interact with their abiotic environment, as well understanding bio ... Full text Cite

Purifying selection, sequence composition, and context-specific indel mutations shape intraspecific variation in a bacterial endosymbiont.

Journal Article Genome biology and evolution · January 2012 Comparative genomics of closely related bacterial strains can clarify mutational processes and selective forces that impact genetic variation. Among primary bacterial endosymbionts of insects, such analyses have revealed ongoing genome reduction, raising q ... Full text Cite

Reduced selective constraint in endosymbionts: elevation in radical amino acid replacements occurs genome-wide.

Journal Article PloS one · January 2011 As predicted by the nearly neutral model of evolution, numerous studies have shown that reduced N(e) accelerates the accumulation of slightly deleterious changes under genetic drift. While such studies have mostly focused on eukaryotes, bacteria also offer ... Full text Cite

Unprecedented loss of ammonia assimilation capability in a urease-encoding bacterial mutualist.

Journal Article BMC genomics · December 2010 BackgroundBlochmannia are obligately intracellular bacterial mutualists of ants of the tribe Camponotini. Blochmannia perform key nutritional functions for the host, including synthesis of several essential amino acids. We used Illumina technology ... Full text Open Access Cite

Using the Wolbachia bacterial symbiont to teach Inquiry-based science: A high school laboratory series

Journal Article American Biology Teacher · October 1, 2010 Inquiry, discovery, and technology are key pillars in improving science education. We present an inquiry-based lab project using the worldwide symbiosis between the bacterium Wolbachia and invertebrates. This endeavor, called "Discover the Microbes Within! ... Full text Cite

Slip into something more functional: selection maintains ancient frameshifts in homopolymeric sequences.

Journal Article Molecular biology and evolution · April 2010 Mutational hotspots offer significant sources of genetic variability upon which selection can act. However, with a few notable exceptions, we know little about the dynamics and fitness consequences of mutations in these regions. Here, we explore evolutiona ... Full text Cite

Genomic erosion and extensive horizontal gene transfer in gut-associated Acetobacteraceae.

Journal Article BMC genomics · June 2019 BackgroundSymbiotic relationships between animals and bacteria have profound impacts on the evolutionary trajectories of each partner. Animals and gut bacteria engage in a variety of relationships, occasionally persisting over evolutionary timesca ... Full text Cite

In it for the long haul: evolutionary consequences of persistent endosymbiosis.

Journal Article Current opinion in genetics & development · December 2017 Phylogenetically independent bacterial lineages have undergone a profound lifestyle shift: from a free-living to obligately host-associated existence. Among these lineages, intracellular bacterial mutualists of insects are among the most intimate, constrai ... Full text Cite

Ancient bacterial endosymbionts of insects: Genomes as sources of insight and springboards for inquiry.

Journal Article Experimental cell research · September 2017 Ancient associations between insects and bacteria provide models to study intimate host-microbe interactions. Currently, a wealth of genome sequence data for long-term, obligately intracellular (primary) endosymbionts of insects reveals profound genomic co ... Full text Cite

Deep divergence and rapid evolutionary rates in gut-associated Acetobacteraceae of ants.

Journal Article BMC microbiology · July 2016 BackgroundSymbiotic associations between gut microbiota and their animal hosts shape the evolutionary trajectories of both partners. The genomic consequences of these relationships are significantly influenced by a variety of factors, including ni ... Full text Cite

Endosymbiont evolution: predictions from theory and surprises from genomes.

Journal Article Annals of the New York Academy of Sciences · December 2015 Genome data have created new opportunities to untangle evolutionary processes shaping microbial variation. Among bacteria, long-term mutualists of insects represent the smallest and (typically) most AT-rich genomes. Evolutionary theory provides a context t ... Full text Cite

Thermally adaptive tradeoffs in closely related marine bacterial strains.

Journal Article Environ Microbiol · July 2015 Time series studies have shown that some bacterial taxa occur only at specific times of the year while others are ubiquitous in spite of seasonal shifts in environmental variables. Here, we ask if these ubiquitous clades are generalists that grow over a wi ... Full text Link to item Cite

Genome evolution in an ancient bacteria-ant symbiosis: parallel gene loss among Blochmannia spanning the origin of the ant tribe Camponotini.

Journal Article PeerJ · January 2015 Stable associations between bacterial endosymbionts and insect hosts provide opportunities to explore genome evolution in the context of established mutualisms and assess the roles of selection and genetic drift across host lineages and habitats. Blochmann ... Full text Cite

Can't take the heat: high temperature depletes bacterial endosymbionts of ants.

Journal Article Microbial ecology · October 2013 Members of the ant tribe Camponotini have coevolved with Blochmannia, an obligate intracellular bacterial mutualist. This endosymbiont lives within host bacteriocyte cells that line the ant midgut, undergoes maternal transmission from host queens to offspr ... Full text Cite

First impressions in a glowing host-microbe partnership.

Journal Article Cell host & microbe · August 2013 Despite the clear significance of beneficial animal-microbe associations, mechanisms underlying their initiation and establishment are rarely understood. In this issue of Cell Host & Microbe, Kremer et al. (2013) reveal that first contact within the squid- ... Full text Cite

Animals in a bacterial world, a new imperative for the life sciences.

Journal Article Proc Natl Acad Sci U S A · February 26, 2013 In the last two decades, the widespread application of genetic and genomic approaches has revealed a bacterial world astonishing in its ubiquity and diversity. This review examines how a growing knowledge of the vast range of animal-bacterial interactions, ... Full text Link to item Cite

Proteomic analysis of an unculturable bacterial endosymbiont (Blochmannia) reveals high abundance of chaperonins and biosynthetic enzymes.

Journal Article J Proteome Res · February 1, 2013 Many insect groups have coevolved with bacterial endosymbionts that live within specialized host cells. As a salient example, ants in the tribe Camponotini rely on Blochmannia, an intracellular bacterial mutualist that synthesizes amino acids and recycles ... Full text Link to item Cite

Sequence context of indel mutations and their effect on protein evolution in a bacterial endosymbiont.

Journal Article Genome biology and evolution · January 2013 Indel mutations play key roles in genome and protein evolution, yet we lack a comprehensive understanding of how indels impact evolutionary processes. Genome-wide analyses enabled by next-generation sequencing can clarify the context and effect of indels, ... Full text Cite

Strategies of genomic integration within insect-bacterial mutualisms.

Journal Article The Biological bulletin · August 2012 Insects, the most diverse group of macroorganisms with 900,000 known species, have been a rich playground for the evolution of symbiotic associations. Symbionts of this enormous animal group include a range of microbial partners. Insects are prone to estab ... Full text Cite

Endosymbiosis.

Journal Article Current biology : CB · July 2012 The phenomenon of endosymbiosis, or one organism living within another, has deeply impacted the evolution of life and continues to shape the ecology of countless species. Traditionally, biologists have viewed evolution as a largely bifurcating pattern, ref ... Full text Cite

Mutualism meltdown in insects: bacteria constrain thermal adaptation.

Journal Article Current opinion in microbiology · June 2012 Predicting whether and how organisms will successfully cope with climate change presents critical questions for biologists and environmental scientists. Models require knowing how organisms interact with their abiotic environment, as well understanding bio ... Full text Cite

Purifying selection, sequence composition, and context-specific indel mutations shape intraspecific variation in a bacterial endosymbiont.

Journal Article Genome biology and evolution · January 2012 Comparative genomics of closely related bacterial strains can clarify mutational processes and selective forces that impact genetic variation. Among primary bacterial endosymbionts of insects, such analyses have revealed ongoing genome reduction, raising q ... Full text Cite

Reduced selective constraint in endosymbionts: elevation in radical amino acid replacements occurs genome-wide.

Journal Article PloS one · January 2011 As predicted by the nearly neutral model of evolution, numerous studies have shown that reduced N(e) accelerates the accumulation of slightly deleterious changes under genetic drift. While such studies have mostly focused on eukaryotes, bacteria also offer ... Full text Cite

Unprecedented loss of ammonia assimilation capability in a urease-encoding bacterial mutualist.

Journal Article BMC genomics · December 2010 BackgroundBlochmannia are obligately intracellular bacterial mutualists of ants of the tribe Camponotini. Blochmannia perform key nutritional functions for the host, including synthesis of several essential amino acids. We used Illumina technology ... Full text Open Access Cite

Using the Wolbachia bacterial symbiont to teach Inquiry-based science: A high school laboratory series

Journal Article American Biology Teacher · October 1, 2010 Inquiry, discovery, and technology are key pillars in improving science education. We present an inquiry-based lab project using the worldwide symbiosis between the bacterium Wolbachia and invertebrates. This endeavor, called "Discover the Microbes Within! ... Full text Cite

Slip into something more functional: selection maintains ancient frameshifts in homopolymeric sequences.

Journal Article Molecular biology and evolution · April 2010 Mutational hotspots offer significant sources of genetic variability upon which selection can act. However, with a few notable exceptions, we know little about the dynamics and fitness consequences of mutations in these regions. Here, we explore evolutiona ... Full text Cite

One nutritional symbiosis begat another: phylogenetic evidence that the ant tribe Camponotini acquired Blochmannia by tending sap-feeding insects.

Journal Article BMC evolutionary biology · December 2009 BackgroundBacterial endosymbiosis has a recurring significance in the evolution of insects. An estimated 10-20% of insect species depend on bacterial associates for their nutrition and reproductive viability. Members of the ant tribe Camponotini, ... Full text Cite

Remaining flexible in old alliances: functional plasticity in constrained mutualisms.

Journal Article DNA and cell biology · August 2009 Central to any beneficial interaction is the capacity of partners to detect and respond to significant changes in the other. Recent studies of microbial mutualists show their close integration with host development, immune responses, and acclimation to a d ... Full text Cite

Endosymbiont gene functions impaired and rescued by polymerase infidelity at poly(A) tracts.

Journal Article Proceedings of the National Academy of Sciences of the United States of America · September 2008 Among host-dependent bacteria that have evolved by extreme reductive genome evolution, long-term bacterial endosymbionts of insects have the smallest (160-790 kb) and most A + T-rich (>70%) bacterial genomes known to date. These genomes are riddled with po ... Full text Cite

Toward a Wolbachia multilocus sequence typing system: discrimination of Wolbachia strains present in Drosophila species.

Journal Article Current microbiology · November 2006 Among the diverse maternally inherited symbionts in arthropods, Wolbachia are the most common and infect over 20% of all species. In a departure from traditional genotyping or phylogenetic methods relying on single Wolbachia genes, the present study repres ... Full text Cite

The tripartite associations between bacteriophage, Wolbachia, and arthropods.

Journal Article PLoS pathogens · May 2006 By manipulating arthropod reproduction worldwide, the heritable endosymbiont Wolbachia has spread to pandemic levels. Little is known about the microbial basis of cytoplasmic incompatibility (CI) except that bacterial densities and percentages of infected ... Full text Cite

Widespread recombination throughout Wolbachia genomes.

Journal Article Molecular biology and evolution · February 2006 Evidence is growing that homologous recombination is a powerful source of genetic variability among closely related free-living bacteria. Here we investigate the extent of recombination among housekeeping genes of the endosymbiotic bacteria Wolbachia. Four ... Full text Cite

The tripartite associations between bacteriophage, Wolbachia, and arthropods

Journal Article PLoS Pathogens · 2006 By manipulating arthropod reproduction worldwide, the heritable endosymbiont Wolbachia has spread to pandemic levels. Little is known about the microbial basis of cytoplasmic incompatibility (CI) except that bacterial densities and percentages of infected ... Full text Cite

Phylogeny of Wolbachia pipientis based on gltA, groEL and ftsZ gene sequences: clustering of arthropod and nematode symbionts in the F supergroup, and evidence for further diversity in the Wolbachia tree.

Journal Article Microbiology (Reading, England) · December 2005 Current phylogenies of the intracellular bacteria belonging to the genus Wolbachia identify six major clades (A-F), termed 'supergroups', but the branching order of these supergroups remains unresolved. Supergroups A, B and E include most of the wolbachiae ... Full text Cite

For better or worse: genomic consequences of intracellular mutualism and parasitism.

Journal Article Current opinion in genetics & development · December 2005 Bacteria that replicate within eukaryotic host cells include a variety of pathogenic and mutualistic species. Early genome data for these intracellular associates suggested they experience continual gene loss, little if any gene acquisition, and minimal re ... Full text Cite

Genome sequence of Blochmannia pennsylvanicus indicates parallel evolutionary trends among bacterial mutualists of insects.

Journal Article Genome research · August 2005 The distinct lifestyle of obligately intracellular bacteria can alter fundamental forces that drive and constrain genome change. In this study, sequencing the 792-kb genome of Blochmannia pennsylvanicus, an obligate endosymbiont of Camponotus pennsylvanicu ... Full text Cite

The roles of positive and negative selection in the molecular evolution of insect endosymbionts.

Journal Article Gene · August 2005 The evolutionary rate acceleration observed in most endosymbiotic bacteria may be explained by higher mutation rates, changes in selective pressure, and increased fixation of deleterious mutations by genetic drift. Here, we explore the forces influencing m ... Full text Cite

Gene expression levels influence amino acid usage and evolutionary rates in endosymbiotic bacteria.

Journal Article Gene · June 2005 Most endosymbiotic bacteria have extremely reduced genomes, accelerated evolutionary rates, and strong AT base compositional bias thought to reflect reduced efficacy of selection and increased mutational pressure. Here, we present a comparative study of ev ... Full text Cite

Nonhomogeneous model of sequence evolution indicates independent origins of primary endosymbionts within the enterobacteriales (gamma-Proteobacteria).

Journal Article Molecular biology and evolution · March 2005 Standard methods of phylogenetic reconstruction are based on models that assume homogeneity of nucleotide composition among taxa. However, this assumption is often violated in biological data sets. In this study, we examine possible effects of nucleotide h ... Full text Cite

Mutation exposed: a neutral explanation for extreme base composition of an endosymbiont genome.

Journal Article Journal of molecular evolution · December 2004 The influence of neutral mutation pressure versus selection on base composition evolution is a subject of considerable controversy. Yet the present study represents the first explicit population genetic analysis of this issue in prokaryotes, the group in w ... Full text Cite

Bacteriophage flux in endosymbionts (Wolbachia): infection frequency, lateral transfer, and recombination rates.

Journal Article Molecular biology and evolution · October 2004 The highly specialized genomes of bacterial endosymbionts typically lack one of the major contributors of genomic flux in the free-living microbial world-bacteriophages. This study yields three results that show bacteriophages have, to the contrary, been i ... Full text Cite

Endosymbiosis: lessons in conflict resolution.

Journal Article PLoS biology · March 2004 Full text Cite

Host-symbiont stability and fast evolutionary rates in an ant-bacterium association: cospeciation of camponotus species and their endosymbionts, candidatus blochmannia.

Journal Article Systematic biology · February 2004 Bacterial endosymbionts are widespread across several insect orders and are involved in interactions ranging from obligate mutualism to reproductive parasitism. Candidatus Blochmannia gen. nov. (Blochmannia) is an obligate bacterial associate of Camponotus ... Full text Cite

A conservative test of genetic drift in the endosymbiotic bacterium Buchnera: slightly deleterious mutations in the chaperonin groEL.

Journal Article Genetics · December 2003 The obligate endosymbiotic bacterium Buchnera aphidicola shows elevated rates of sequence evolution compared to free-living relatives, particularly at nonsynonymous sites. Because Buchnera experiences population bottlenecks during transmission to the offsp ... Full text Cite

Gene expression level influences amino acid usage, but not codon usage, in the tsetse fly endosymbiont Wigglesworthia.

Journal Article Microbiology (Reading, England) · September 2003 Wigglesworthia glossinidia brevipalpis, the obligate bacterial endosymbiont of the tsetse fly Glossina brevipalpis, is characterized by extreme genome reduction and AT nucleotide composition bias. Here, multivariate statistical analyses are used to test th ... Full text Cite

Genome evolution in an insect cell: distinct features of an ant-bacterial partnership.

Journal Article The Biological bulletin · April 2003 Bacteria that live exclusively within eukaryotic host cells include not only well-known pathogens, but also obligate mutualists, many of which occur in diverse insect groups such as aphids, psyllids, tsetse flies, and the ant genus Camponotus (Buchner, 196 ... Full text Cite

Genome evolution in bacterial endosymbionts of insects.

Journal Article Nature reviews. Genetics · November 2002 Many insect species rely on intracellular bacterial symbionts for their viability and fecundity. Large-scale DNA-sequence analyses are revealing the forces that shape the evolution of these bacterial associates and the genetic basis of their specialization ... Full text Cite

A strong effect of AT mutational bias on amino acid usage in Buchnera is mitigated at high-expression genes.

Journal Article Molecular biology and evolution · September 2002 The advent of full genome sequences provides exceptionally rich data sets to explore molecular and evolutionary mechanisms that shape divergence among and within genomes. In this study, we use multivariate analysis to determine the processes driving genome ... Full text Cite

Small genome of Candidatus Blochmannia, the bacterial endosymbiont of Camponotus, implies irreversible specialization to an intracellular lifestyle.

Journal Article Microbiology (Reading, England) · August 2002 Blochmannia (Candidatus Blochmannia gen. nov.) is the primary bacterial endosymbiont of the ant genus CAMPONOTUS: Like other obligate endosymbionts of insects, Blochmannia occurs exclusively within eukaryotic cells and has experienced long-term vertical tr ... Full text Cite

50 million years of genomic stasis in endosymbiotic bacteria.

Journal Article Science (New York, N.Y.) · June 2002 Comparison of two fully sequenced genomes of Buchnera aphidicola, the obligate endosymbionts of aphids, reveals the most extreme genome stability to date: no chromosome rearrangements or gene acquisitions have occurred in the past 50 to 70 million years, d ... Full text Cite

Parallel acceleration of evolutionary rates in symbiont genes underlying host nutrition.

Journal Article Molecular phylogenetics and evolution · June 2001 The overproduction of essential amino acids by Buchnera aphidicola, the primary bacterial mutualist of aphids, is considered an adaptation for increased production of nutrients that are lacking in aphids' diet of plant sap. Given their shared role in host ... Full text Cite

Intraspecific variation in symbiont genomes: bottlenecks and the aphid-buchnera association.

Journal Article Genetics · February 2001 Buchnera are maternally transmitted bacterial endosymbionts that synthesize amino acids that are limiting in the diet of their aphid hosts. Previous studies demonstrated accelerated sequence evolution in Buchnera compared to free-living bacteria, especiall ... Full text Cite

Vertical transmission of biosynthetic plasmids in aphid endosymbionts (Buchnera).

Journal Article Journal of bacteriology · January 2001 This study tested for horizontal transfer of plasmids among Buchnera aphidicola strains associated with ecologically and phylogenetically related aphid hosts (Uroleucon species). Phylogenetic congruence of Buchnera plasmid (trpEG and leuABC) and chromosoma ... Full text Cite

Intraspecific phylogenetic congruence among multiple symbiont genomes.

Journal Article Proceedings. Biological sciences · December 2000 Eukaryotes often form intimate endosymbioses with prokaryotic organisms. Cases in which these symbionts are transmitted cytoplasmically to host progeny create the potential for co-speciation or congruent evolution among the distinct genomes of these partne ... Full text Cite

Lifestyle evolution in symbiotic bacteria: insights from genomics.

Journal Article Trends in ecology & evolution · August 2000 Bacteria that live only in eukaryotic cells and tissues, including chronic pathogens and mutualistic bacteriocyte associates, often possess a distinctive set of genomic traits, including reduced genome size, biased nucleotide base composition and fast poly ... Full text Cite

Decay of mutualistic potential in aphid endosymbionts through silencing of biosynthetic loci: Buchnera of Diuraphis.

Journal Article Proceedings. Biological sciences · July 2000 Buchnera, the primary bacterial endosymbiont of aphids, is known to provision essential amino acids lacking in the hosts' diet of plant sap. The recent discovery of silenced copies of genes for tryptophan biosynthesis (trpEG) in certain Buchnera lineages s ... Full text Cite

Decoupling of genome size and sequence divergence in a symbiotic bacterium.

Journal Article Journal of bacteriology · July 2000 In contrast to genome size variation in most bacterial taxa, the small genome size of Buchnera sp. was shown to be highly conserved across genetically diverse isolates (630 to 643 kb). This exceptional size conservation may reflect the inability of this ob ... Full text Cite

Cospeciation between bacterial endosymbionts (Buchnera) and a recent radiation of aphids (Uroleucon) and pitfalls of testing for phylogenetic congruence.

Journal Article Evolution; international journal of organic evolution · April 2000 Previous studies of phylogenetic congruence between aphids and their symbiotic bacteria (Buchnera) supported long-term vertical transmission of symbionts. However, those studies were based on distantly related aphids and would not have revealed horizontal ... Full text Cite

Evidence for genetic drift in endosymbionts (Buchnera): analyses of protein-coding genes.

Journal Article Molecular biology and evolution · January 1999 Buchnera, the bacterial endosymbionts of aphids, undergo severe population bottlenecks during maternal transmission through their hosts. Previous studies suggest an increased effect of drift within these strictly asexual, small populations, resulting in an ... Full text Cite

Comparison of the evolutionary dynamics of symbiotic and housekeeping loci: a case for the genetic coherence of rhizobial lineages.

Journal Article Molecular biology and evolution · January 1999 In prokaryotes, lateral gene transfer across chromosomal lineages may be mediated by plasmids, phages, transposable elements, and other accessory DNA elements. However, the importance of such transfer and the evolutionary forces that may restrict gene exch ... Full text Cite

Rhizobium gone native: unexpected plasmid stability of indigenous Rhizobium leguminosarum.

Journal Article Proceedings of the National Academy of Sciences of the United States of America · May 1997 Lateral transfer of bacterial plasmids is thought to play an important role in microbial evolution and population dynamics. However, this assumption is based primarily on investigations of medically or agriculturally important bacterial species. To explore ... Full text Cite