The widespread occurrence of sex is one of the most elusive problems in evolutionary biology. Theory predicts that asexual lineages can be driven to extinction by uncontrolled proliferation of vertically transmitted transposable elements (TEs), which accumulate because of the inefficiency of purifying selection in the absence of sex and recombination. To test this prediction, we compared genome-wide TE load between a sexual lineage of the parasitoid wasp Leptopilina clavipes and a lineage of the same species that is rendered asexual by Wolbachia-induced parthenogenesis. We obtained draft genome sequences at 15-20× coverage of both the sexual and the asexual lineages using next-generation sequencing. We identified transposons of most major classes in both lineages. Quantification of TE abundance using coverage depth showed that copy numbers in the asexual lineage exceeded those in the sexual lineage for DNA transposons, but not LTR and LINE-like elements. However, one or a small number of gypsy-like LTR elements exhibited a fourfold higher coverage in the asexual lineage. Quantitative PCR showed that high loads of this gypsy-like TE were characteristic for 11 genetically distinct asexual wasp lineages when compared to sexual lineages. We found no evidence for an overall increase in copy number for all TE types in asexuals as predicted by theory. Instead, we suggest that the expansions of specific TEs are best explained as side effects of (epi)genetic manipulations of the host genome by Wolbachia. Asexuality is achieved in a myriad of ways in nature, many of which could similarly result in TE proliferation.
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Stud Mycol
December 2024
Universidade de Lisboa, Faculdade de Ciências, Biosystems and Integrative Sciences Institute (BioISI), Campo Grande, 1749-016 Lisbon, Portugal.
The application of traditional morphological and ecological species concepts to closely related, asexual fungal taxa is challenging due to the lack of distinctive morphological characters and frequent cosmopolitan and plurivorous behaviour. As a result, multilocus sequence analysis (MLSA) has become a powerful and widely used tool to recognise and delimit independent evolutionary lineages (IEL) in fungi. However, MLSA can mask discordances in individual gene trees and lead to misinterpretation of speciation events.
View Article and Find Full Text PDFParasit Vectors
December 2024
Department of Evolution, Ecology and Behaviour, University of Liverpool, Liverpool, L69 7ZB, UK.
Background: Strongyloides nematodes are livestock parasites, and Strongyloides papillosus infecting ruminant livestock can cause disease. Recent genomic analysis of several Strongyloides species is now facilitating population genomic analyses of natural Strongyloides infections, for example finding that Strongyloides ratti in wild UK rats exists as an assemblage of long-lived, asexual lineages.
Methods: Here we have initiated an investigation into the population genomics of S.
Int J Mol Sci
December 2024
Ministry of Education Key Laboratory for Transboundary Ecosecurity of Southwest China, Yunnan Key Laboratory of Plant Reproductive Adaptation and Evolutionary Ecology, Institute of Biodiversity, School of Ecology and Environmental Science, Yunnan University, Kunming 650504, China.
Transgenerational plasticity (TGP) refers to the influence of ancestral environmental signals on offspring's traits across generations. While evidence of TGP in plants is growing, its role in plant adaptation over successive generations remains unclear, particularly in floating plants facing fluctuating environments. Duckweed (), a common ecological remediation material, often coexists with the harmful bloom-forming cyanobacterium , which releases a highly toxic exudate mixture (MaE) during its growth.
View Article and Find Full Text PDFMol Plant Pathol
December 2024
Department of Biology, University of Oxford, Oxford, UK.
Fungal plant pathogens cause major crop losses worldwide, with many featuring compartmentalised genomes that include both core and accessory regions, which are believed to drive adaptation. The highly host-specific fungus Colletotrichum lupini greatly impacts lupin (Lupinus spp.) cultivation.
View Article and Find Full Text PDFSci Rep
December 2024
Department of Fish Ecology and Evolution, Swiss Federal Institute of Aquatic Science and Technology (EAWAG), Kastanienbaum, Switzerland.
The presence or absence of sex can have a strong influence on the processes whereby species arise. Yet, the mechanistic underpinnings of this influence are poorly understood. To gain insights into the mechanisms whereby the reproductive mode may influence ecological diversification, we investigate how natural selection, genetic mixing, and the reproductive mode interact and how this interaction affects the evolutionary dynamics of diversifying lineages.
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