Genomic Signature of Sexual Reproduction in the Bdelloid Rotifer Macrotrachella quadricornifera

Genetics ◽  
2021 ◽  
Author(s):  
Veronika N Laine ◽  
Timothy Sackton ◽  
Matthew Meselson
Keyword(s):  
Sexual Reproduction ◽  
Genomic Signature ◽  
Allele Sharing ◽  
Bdelloid Rotifer ◽  
Freshwater Invertebrates ◽  
Bdelloid Rotifers ◽  
Worldwide Distribution

Abstract Bdelloid rotifers, common freshwater invertebrates of ancient origin and worldwide distribution have long been thought to be entirely asexual, being the principal exception to the view that in eukaryotes the loss of sex leads to early extinction. That bdelloids are facultatively sexual is shown by a study of allele sharing within a group of closely related bdelloids of the species Macrotrachella quadricornifera, supporting the view that sexual reproduction is essential for long-term success in all eukaryotes.

scholarly journals Sexual Reproduction in Bdelloid Rotifers

2020 ◽  
Author(s):  
Veronika N. Laine ◽  
Timothy Sackton ◽  
Matthew Meselson
Keyword(s):  
Sexual Reproduction ◽  
Allele Sharing ◽  
Evolution Theory ◽  
Epistatic Interactions ◽  
Bdelloid Rotifers ◽  
Genome Wide ◽  
Growing Body ◽  
Macrotrachela Quadricornifera ◽  
Evolutionary Success

ABSTRACTNearly all eukaryotes reproduce sexually, either constitutively or facultatively, and nearly all that are thought to be asexual arose recently from sexuals, suggesting that loss of sex leads to early extinction. In apparent exception, there are several groups of ancient origin that have been thought to be entirely asexual. Of these, the most extensively studied are the rotifers of Class Bdelloidea. Yet the evidence for their asexuality is entirely negative -- the failure to establish the existence of males or hermaphrodites. Nevertheless, there is a growing body of evidence that bdelloids do reproduce sexually, albeit rarely, retaining meiosis-associated genes and, in a limited study of allele sharing in the bdelloid Macrotrachela quadricornifera, displaying a pattern of genetic exchange indicating recent sexual reproduction. Here we present a much larger study of allele sharing in the same system, clearly showing the occurrence of sexual reproduction, thereby removing the principal challenge to the generalization that sexual reproduction is essential for long-term evolutionary success in eukaryotes. We also discuss the relation between bdelloid life history and population structure and a possible benefit of outcrossing in restoring beneficial genome-wide epistatic interactions disrupted by loss of heterozygosity.STATEMENT OF SIGNIFICANCEMany hypotheses have been advanced to explain why, despite its substantial costs, sexual reproduction is nearly universal in eukaryotes and why the loss of sex generally leads to early extinction--a major problem in current evolution theory. Posing a challenge to all such hypotheses are a few groups of ancient origin that have been thought to be entirely asexual. Of these, the most extensively studied are the rotifers of Class Bdelloidea. Here we show that a bdelloid species is facultatively sexual, removing what had been a long-standing challenge to hypotheses for the benefit of sex. We also suggest that genome-wide beneficial epistasis may contribute to the advantage of sex over asex in diploids and to the predominance of diploidy over haploidy in eukaryotes.

scholarly journals Genomic signatures of recombination in a natural population of the bdelloid rotifer Adineta vaga

2020 ◽  
Vol 11 (1) ◽  
Author(s):  
Olga A. Vakhrusheva ◽  
Elena A. Mnatsakanova ◽  
Yan R. Galimov ◽  
Tatiana V. Neretina ◽  
Evgeny S. Gerasimov ◽  
...  
Keyword(s):  
Genetic Variation ◽  
Linkage Disequilibrium ◽  
Sexual Reproduction ◽  
Genetic Exchange ◽  
Bdelloid Rotifer ◽  
Present Evidence ◽  
Bdelloid Rotifers ◽  
Genomic Signatures ◽  
Dead End ◽  
Whole Genomes

AbstractSexual reproduction is almost ubiquitous among extant eukaryotes. As most asexual lineages are short-lived, abandoning sex is commonly regarded as an evolutionary dead end. Still, putative anciently asexual lineages challenge this view. One of the most striking examples are bdelloid rotifers, microscopic freshwater invertebrates believed to have completely abandoned sexual reproduction tens of Myr ago. Here, we compare whole genomes of 11 wild-caught individuals of the bdelloid rotifer Adineta vaga and present evidence that some patterns in its genetic variation are incompatible with strict clonality and lack of genetic exchange. These patterns include genotype proportions close to Hardy-Weinberg expectations within loci, lack of linkage disequilibrium between distant loci, incongruent haplotype phylogenies across the genome, and evidence for hybridization between divergent lineages. Analysis of triallelic sites independently corroborates these findings. Our results provide evidence for interindividual genetic exchange and recombination in A. vaga, a species previously thought to be anciently asexual.

scholarly journals Recombination in a natural population of the bdelloid rotifer Adineta vaga

2018 ◽  
Author(s):  
Olga A. Vakhrusheva ◽  
Elena A. Mnatsakanova ◽  
Yan R. Galimov ◽  
Tatiana V. Neretina ◽  
Evgeny S. Gerasimov ◽  
...  
Keyword(s):  
Genetic Structure ◽  
Adaptive Radiation ◽  
Wild Population ◽  
Bdelloid Rotifer ◽  
Bdelloid Rotifers ◽  
Stick Insects ◽  
Complete Genomes ◽  
Long Term Consequences ◽  
Rule Out

Sexual reproduction which involves alternation of meiosis and syngamy is the ancestral condition of extant eukaryotes. Transitions to asexual reproduction were numerous, but most of the resulting eukaryotic lineages are rather short-lived. Still, there are several exceptions to this rule including darwinulid ostracods1,2 and timema stick insects3. The most striking of them is bdelloid rotifers4–6, microscopic freshwater invertebrates which underwent an extensive adaptive radiation after apparently losing meiosis over 10 Mya. Indeed, both the lack of males in numerous bdelloid species and the lack of proper homology between chromosomes6 rule out ordinary sex. However, this does not exclude the possibility of some other mode of interindividual genetic exchange and recombination in their populations7. Recent analyses based on a few loci suggested genetic exchanges in this group8,9, although this has been controversial10. Here, we compare complete genomes of 11 individuals from the wild population of the bdelloid rotifer Adineta vaga, and show that its genetic structure, which involves Hardy-Weinberg proportions of genotypes within loci and lack of linkage disequilibrium between distant loci, is incompatible with strictly clonal reproduction. Instead, it can emerge only under ongoing recombination between different individuals within this species, possibly through transformation. Such a genetic structure makes the population immune to negative long-term consequences of the loss of conventional meiosis11, although this does not necessarily imply that interindividual genetic exchanges in A. vaga are directly maintained by natural selection.

scholarly journals Sexual reproduction with variable mating systems can resist asexuality in a rock–paper–scissors dynamics

2015 ◽  
Vol 2 (7) ◽  
pp. 140383 ◽  
Author(s):  
Juan Carranza ◽  
Vicente Polo
Keyword(s):  
Mating System ◽  
Sexual Reproduction ◽  
Parameter Space ◽  
Mating Systems ◽  
Reproductive Mode ◽  
Long Term Effects ◽  
Diploid Population ◽  
Theoretical Question ◽  
Equal Contribution

While sex can be advantageous for a lineage in the long term, we still lack an explanation for its maintenance with the twofold cost per generation. Here we model an infinite diploid population where two autosomal loci determine, respectively, the reproductive mode, sexual versus asexual and the mating system, polygynous (costly sex) versus monogamous (assuming equal contribution of parents to offspring, i.e. non-costly sex). We show that alleles for costly sex can spread when non-costly sexual modes buffer the interaction between asexual and costly sexual strategies, even without twofold benefit of recombination with respect to asexuality. The three interacting strategies have intransitive fitness relationships leading to a rock–paper–scissors dynamics, so that alleles for costly sex cannot be eliminated by asexuals in most situations throughout the parameter space. Our results indicate that sexual lineages with variable mating systems can resist the invasion of asexuals and allow for long-term effects to accumulate, thus providing a solution to the persisting theoretical question of why sex was not displaced by asexuality along evolution.

Mating type segregation in Choanephora cucurbitarum following sexual reproduction

1996 ◽  
Vol 74 (6) ◽  
pp. 919-923 ◽  
Author(s):  
M. Q. Yu ◽  
W. H. Ko
Keyword(s):  
Sexual Reproduction ◽  
Mating Type ◽  
Long Term Storage ◽  
Respective Parent ◽  
Choanephora Cucurbitarum ◽  
The Cross ◽  
Term Storage ◽  
Hyphal Fragment

Zygospore progeny from the cross between + and − isolates of Choanephora cucurbitarum consisted of +, −, and ± types. The + and − zygospore isolates were stable, giving rise to hyphal fragment cultures and sporangiospores with the same mating type as their respective parent. However, the ± zygospore isolates were unstable, segregating to +, −, and ± types during asexual propagations. During long-term storage, the + and − isolates were also very stable, but ± isolates were not. All the ± isolates originating from single zygospores, hyphal fragments, or sporangiospores produced azygospores, suggesting that azygospores of this fungus are produced by mating-type heterokaryotic mycelia. Keywords: azygospore, Choanephora cucurbitarum, germsporangiospore, germsporangium, zygospore germination.

scholarly journals TECHNOLOGIES FOR LARGE DATA MANAGEMENT IN SCIENTIFIC COMPUTING

2014 ◽  
Vol 25 (02) ◽  
pp. 1430001 ◽  
Author(s):  
ALBERTO PACE
Keyword(s):  
Data Management ◽  
High Energy Physics ◽  
Hadron Collider ◽  
Scientific Research ◽  
Large Data ◽  
High Energy ◽  
Worldwide Distribution ◽  
Systematic Collection ◽  
Energy Physics

In recent years, intense usage of computing has been the main strategy of investigations in several scientific research projects. The progress in computing technology has opened unprecedented opportunities for systematic collection of experimental data and the associated analysis that were considered impossible only few years ago. This paper focuses on the strategies in use: it reviews the various components that are necessary for an effective solution that ensures the storage, the long term preservation, and the worldwide distribution of large quantities of data that are necessary in a large scientific research project. The paper also mentions several examples of data management solutions used in High Energy Physics for the CERN Large Hadron Collider (LHC) experiments in Geneva, Switzerland which generate more than 30,000 terabytes of data every year that need to be preserved, analyzed, and made available to a community of several tenth of thousands scientists worldwide.

scholarly journals Bdelloid rotifers use hundreds of horizontally acquired genes against fungal pathogens

2021 ◽  
Author(s):  
Reuben W Nowell ◽  
Timothy G Barraclough ◽  
Christopher G Wilson
Keyword(s):  
Fungal Pathogen ◽  
Cell Walls ◽  
Fungal Pathogens ◽  
Fungal Cell ◽  
Bdelloid Rotifers ◽  
Fungal Toxins ◽  
Foreign Genes ◽  
Fungal Cell Walls

Obligately asexual lineages are typically rare and short-lived. According to one hypothesis, they adapt too slowly to withstand relentlessly coevolving pathogens. Bdelloid rotifers seem to have avoided this fate, by enduring millions of years without males or sex. We investigated whether bdelloids' unusual capacity to acquire non-metazoan genes horizontally has enhanced their resistance to pathogens. We found that horizontally transferred genes are three times more likely than native genes to be upregulated in response to a natural fungal pathogen. This enrichment was twofold stronger than that elicited by a physical stressor (desiccation), and the genes showed little overlap. Among hundreds of upregulated non-metazoan genes were RNA ligases putatively involved in resisting fungal toxins and glucanases predicted to bind to fungal cell walls, acquired from bacteria. Our results provide evidence that bdelloids mitigate a predicted challenge of long-term asexuality in part through their ability to acquire and deploy so many foreign genes.

scholarly journals A Review of Scabies: An Infestation More than Skin Deep

Dermatology ◽  
2018 ◽  
Vol 235 (2) ◽  
pp. 79-90 ◽  
Author(s):  
David J. Chandler ◽  
Lucinda C. Fuller
Keyword(s):  
World Health Organisation ◽  
Clinical Situation ◽  
World Health ◽  
Residential Home ◽  
The Past ◽  
Care Services ◽  
Worldwide Distribution ◽  
Health And Social Care ◽  
Variable Impact

Human scabies, a common infestation, has a worldwide distribution with a variable impact and presentation depending on the clinical situation. In developed, high-income settings, health institution and residential home outbreaks challenge health and social care services. In resource-poor settings, it is the downstream sequelae of staphylococcal and streptococcal bacteraemia, induced by scratching, which have a significant impact on the long-term health of communities. Over the past decade scabies has been recognised as a “neglected tropical disease” (NTD) by the World Health Organisation, has an accepted practical system of global diagnostic criteria and is being adopted into integrated programmes of mass drug administration for NTDs in field settings. This review seeks to summarise the recent advances in the understanding of scabies and highlight the advocacy and research headlines with their implication for diagnosis and management of outbreaks and individuals. In addition, it will indicate the priorities and questions that remain.

Genomic Perspectives on the Long-Term Absence of Sexual Reproduction in Animals

2011 ◽  
pp. 223-242 ◽  
Author(s):  
Etienne G. J. Danchin ◽  
Jean-François Flot ◽  
Laetitia Perfus-Barbeoch ◽  
Karine Van Doninck
Keyword(s):  
Sexual Reproduction
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