Microsporidia with Vertical Transmission Were Likely Shaped by Nonadaptive Processes.

Autor:	Haag KL; Department of Genetics and Post-Graduation Program of Genetics and Molecular Biology, Federal University of Rio Grande do Sul, Porto Alegre, Brazil., Pombert JF; Department of Biology, Illinois Institute of Technology., Sun Y; Department of Biology, Illinois Institute of Technology., de Albuquerque NRM; Department of Genetics and Post-Graduation Program of Genetics and Molecular Biology, Federal University of Rio Grande do Sul, Porto Alegre, Brazil., Batliner B; Department of Biology, Illinois Institute of Technology., Fields P; Department of Environmental Sciences, Zoology, Basel University, Switzerland., Lopes TF; Department of Genetics and Post-Graduation Program of Genetics and Molecular Biology, Federal University of Rio Grande do Sul, Porto Alegre, Brazil., Ebert D; Department of Environmental Sciences, Zoology, Basel University, Switzerland.
Jazyk:	angličtina
Zdroj:	Genome biology and evolution [Genome Biol Evol] 2020 Jan 01; Vol. 12 (1), pp. 3599-3614.
DOI:	10.1093/gbe/evz270
Abstrakt:	Microsporidia have the leanest genomes among eukaryotes, and their physiological and genomic simplicity has been attributed to their intracellular, obligate parasitic life-style. However, not all microsporidia genomes are small or lean, with the largest dwarfing the smallest ones by at least an order of magnitude. To better understand the evolutionary mechanisms behind this genomic diversification, we explore here two clades of microsporidia with distinct life histories, Ordospora and Hamiltosporidium, parasitizing the same host species, Daphnia magna. Based on seven newly assembled genomes, we show that mixed-mode transmission (the combination of horizontal and vertical transmission), which occurs in Hamiltosporidium, is found to be associated with larger and AT-biased genomes, more genes, and longer intergenic regions, as compared with the exclusively horizontally transmitted Ordospora. Furthermore, the Hamiltosporidium genome assemblies contain a variety of repetitive elements and long segmental duplications. We show that there is an excess of nonsynonymous substitutions in the microsporidia with mixed-mode transmission, which cannot be solely attributed to the lack of recombination, suggesting that bursts of genome size in these microsporidia result primarily from genetic drift. Overall, these findings suggest that the switch from a horizontal-only to a mixed mode of transmission likely produces population bottlenecks in Hamiltosporidium species, therefore reducing the effectiveness of natural selection, and allowing their genomic features to be largely shaped by nonadaptive processes. (© The Author(s) 2020. Published by Oxford University Press on behalf of the Society for Molecular Biology and Evolution.)
Databáze:	MEDLINE
Externí odkaz:	Zobrazit plný text záznamu