Selfish Genetic Elements and Genomic Conflicts: An Update on Microbial Elements, Their Genetics and Evolutionary Consequences

Abstract

Selfish genetic elements (SGEs) are DNA sequences that enhance their own transmission, often at the expense of the host genome’s overall fitness. They include transposable elements, meiotic drivers, supernumerary B chromosomes, post-segregation killers, and sex-distorting heritable microbes or organelles. These elements generate genetic conflict among different parts of the genome—such as between nuclear, cytoplasmic, and mobile elements—due to their differing transmission strategies. Genomic research has revealed that microbial genomes are abundant in mobile genetic elements (MGEs) that spread through DNA transfer mechanisms and play major roles in genome organization, regulation, and evolution. SGEs contribute to genetic diversity, drive innovation, and influence key biological processes such as gene regulation, development, and speciation. The review highlights the diversity of SGE transmission mechanisms, the domestication of SGEs leading to novel genes and regulatory systems, and their dual role in promoting adaptability while imposing metabolic and genetic costs on the host. Moreover, understanding SGE-driven conflicts provides valuable insights for biotechnology, including the development of gene-editing tools, genetic engineering strategies, and potential therapeutic applications such as targeting cancer.