Suppression of sex-ratio drive in Drosophila subobscura.

Selfish genetic elements (SGEs) enjoy an evolutionary advantage by enhancing their own transmission to offspring, and their genetic suppressors are favoured when they re-establish fair inheritance patterns. Here, we study an X-linked Sex Ratio drive system (SR) in Drosophila subobscura, which kills Y-bearing sperm of SR males, resulting in the over-transmission of the SR-chromosome and a strong female-bias in their offspring. We surveyed D.

Variable prevalence of protective Spiroplasma infection over time in two natural populations of Drosophila hydei.

The temporal dynamics of protective symbionts have rarely been characterized outside of aphid hosts. Here, we determine the prevalence of Spiroplasma in two populations of Drosophila hydei where Spiroplasma infection had been previously recorded (UK and Japan). We observe that infection in both populations is variable over time and confirm the persistence of Spiroplasma in the UK population for 9 years.

Development of Antisense Tools to Study Bodo saltans and Its Intracellular Symbiont.

Obligate symbioses are common in nature and present a particular challenge for functional genetic analysis. In many cases, the host is a non-model species with poor tools for genetic manipulation, and the symbiont cannot be cultured or its gene expression manipulated to investigate function. Here, we investigated the potential for using antisense inhibition to analyze host and symbiont gene function within an obligate aquatic symbiosis.

The Honeybee Associate Galleria mellonella Can Acquire Arsenophonus apicola Through Oral and Parenteral Infection Routes.

Members of the genus Arsenophonus are classically considered to be vertically transmitted endosymbiotic associates of invertebrates. Acquisition of Arsenophonus apicola by Apis mellifera honeybees through social and environmental pathways raises the possibility that this species can infect a broader range of host species. In this study, we tested whether a natural inhabitant of bee hives, the wax moth Galleria mellonella, was a suitable host for A.

Evolution of Wolbachia male-killing mechanism within a host species.

Male-killing bacterial symbionts, prevalent in arthropods, skew population sex ratios by selectively killing male progeny, profoundly impacting ecology and the evolution of their hosts. Male killing is a convergently evolved trait, with microbes evolving diverse male-killing mechanisms across host species with widely divergent sex determination pathways. A common evolutionary response to male-killing presence is the spread of suppressor mutations that restore male survival.

Prevalence of Heritable Symbionts in Parisian Bedbugs (Hemiptera: Cimicidae).

Like many insects, the biology of bedbugs is impacted by a range of partner heritable microbes. Three maternally inherited symbionts are recognised: Wolbachia (an obligate partner), Symbiopectobacterium purcellii strain SyClec, and Candidatus Tisiphia sp. (facultative symbionts typically present in some but not all individuals).

The Hypolimnas misippus Genome Supports a Common Origin of the W Chromosome in Lepidoptera.

Moths and butterflies (Lepidoptera) have a heterogametic sex chromosome system with females carrying ZW chromosomes and males ZZ. The lack of W chromosomes in early-diverging lepidopteran lineages has led to the suggestion of an ancestral Z0 system in this clade and a B chromosome origin of the W. This contrasts with the canonical model of W chromosome evolution in which the W would have originated from the same homologous autosomal pair as the Z chromosome.

and again: the repeated use of two mimicry hotspot loci.

The extent to which evolution is repeatable has been a debated topic among evolutionary biologists. Although rewinding the tape of life perhaps would not lead to the same outcome every time, repeated evolution of analogous genes for similar functions has been extensively reported. Wing phenotypes of butterflies and moths have provided a wealth of examples of gene re-use, with certain 'hotspot loci' controlling wing patterns across diverse taxa.

Male-killer symbiont screening reveals novel associations in ladybirds.

While male-killing bacteria are known to infect across arthropods, ladybird beetles represent a hotspot for these symbioses. In some host species, there are multiple different symbionts that vary in presence and frequency between populations. To further our understanding of spatial and frequency variation, we tested for the presence of three male-killing bacteria: , and , in two ladybird species from a previously unexplored UK population.

The son-killer microbe Arsenophonus nasoniae is a widespread associate of the parasitic wasp Nasonia vitripennis in Europe.

Heritable microbes that exhibit reproductive parasitism are common in insects. One class of these are the male-killing bacteria, which are found in a broad range of insect hosts. Commonly, our knowledge of the incidence of these microbes is based on one or a few sampling sites, and the degree and causes of spatial variation are unclear.

One strain may hide another: Cryptic male-killing Wolbachia.

While heritable symbionts are common in insects, strains that act as male-killers are considered rare. A new study in PLOS Biology identifies a novel male-killer hidden by coinfection and host resistance, highlighting the complexity of host-microbial interactions in natural systems.

History matters: Thermal environment before but not during wasp attack determines the efficiency of symbiont-mediated protection.

The outcome of natural enemy attack in insects is commonly impacted by the presence of defensive microbial symbionts residing within the host. The thermal environment is a factor known to affect symbiont-mediated traits in insects. Lower temperatures, for instance, have been shown to reduce Spiroplasma-mediated protection in Drosophila.

' Megaira' are diverse symbionts of algae and ciliates with the potential for defensive symbiosis.

Symbiotic microbes from the genus Megaira' () are known to be common associates of algae and ciliates. However, genomic resources for these bacteria are scarce, limiting our understanding of their diversity and biology. We therefore utilize Sequence Read Archive and metagenomic assemblies to explore the diversity of this genus.

Isolation, culture and characterization of symbionts from two insect species reveal loss of infectious transmission and extended host range.

Vertically transmitted "Heritable" microbial symbionts represent an important component of the biology and ecology of invertebrates. These symbioses evolved originally from ones where infection/acquisition processes occurred within the environment (horizontal transmission). However, the pattern of evolution that follows transition from horizontal to vertical transmission is commonly obscured by the distant relationship between microbes with differing transmission modes.

Rapid divergence in independent aspects of the compatibility phenotype in a interaction.

Heritable symbionts represent important components of the biology, ecology and evolution of their arthropod hosts. Particular microbial taxa have become common across arthropods as a consequence of their ability to establish in new host species. For a host shift to occur, the symbiont must be exposed to a novel host and then be compatible: it must not cause excess pathology, must have good vertical transmission and must possess a drive phenotype that enables spread.

sp. nov., isolated from the honeybee .

The genus has been traditionally considered to comprise heritable bacterial symbionts of arthropods. Recent work has reported a microbe related to the type species as infecting the honey bee, . The association was unusual for members of the genus in that the microbe-host interaction arose through environmental and social exposure rather than vertical transmission.

, gen. nov., sp. nov., isolated from the leafhopper .

Bacterial endosymbionts are found in multiple arthropod species, where they play crucial roles as nutritional symbionts, defensive symbionts or reproductive parasites. Recent work has highlighted a new clade of heritable microbes within the gammaproteobacteria that enter into both obligate and facultative symbioses, with an obligately required unculturable symbiont recently given the name Symbiopectobacterium. In this study, we describe a culturable rod shaped non-flagellated bacterial symbiont from this clade isolated from the leafhopper .

Genomic diversity across the Rickettsia and 'Candidatus Megaira' genera and proposal of genus status for the Torix group.

Members of the bacterial genus Rickettsia were originally identified as causative agents of vector-borne diseases in mammals. However, many Rickettsia species are arthropod symbionts and close relatives of 'Candidatus Megaira', which are symbiotic associates of microeukaryotes. Here, we clarify the evolutionary relationships between these organisms by assembling 26 genomes of Rickettsia species from understudied groups, including the Torix group, and two genomes of 'Ca.

Inheritance through the cytoplasm.

Most heritable information in eukaryotic cells is encoded in the nuclear genome, with inheritance patterns following classic Mendelian segregation. Genomes residing in the cytoplasm, however, prove to be a peculiar exception to this rule. Cytoplasmic genetic elements are generally maternally inherited, although there are several exceptions where these are paternally, biparentally or doubly-uniparentally inherited.

Sex determination systems as the interface between male-killing bacteria and their hosts.

Arthropods host a range of sex-ratio-distorting selfish elements, including diverse maternally inherited endosymbionts that solely kill infected males. Male-killing heritable microbes are common, reach high frequency, but until recently have been poorly understood in terms of the host-microbe interaction. Additionally, while male killing should generate strong selection for host resistance, evidence of this has been scant.

Positive selection on mitochondria may eliminate heritable microbes from arthropod populations.

Diverse eukaryotic taxa carry facultative heritable symbionts, microbes that are passed from mother to offspring. These symbionts are coinherited with mitochondria, and selection favouring either new symbionts, or new symbiont variants, is known to drive loss of mitochondrial diversity as a correlated response. More recently, evidence has accumulated of episodic directional selection on mitochondria, but with currently unknown consequences for symbiont evolution.