Bartolomé Husson, CarolinaBuendía Abad, MaríaOrnosa Gallego, ConcepciónRúa Tarín, María del Pilar de laMartín Hernández, RaquelHiges Pascual, MarianoMaside Rodríguez, Xulio Manuel2023-02-132023-02-132022Microbial Ecology volume 84, pages856–867 (2022)0095-3628http://hdl.handle.net/10347/30062Trypanosomatids are among the most prevalent parasites in bees but, despite the fact that their impact on the colonies can be quite important and that their infectivity may potentially depend on their genotypes, little is known about the population diversity of these pathogens. Here we cloned and sequenced three non-repetitive single copy loci (DNA topoisomerase II, glyceraldehyde-3-phosphate dehydrogenase and RNA polymerase II large subunit, RPB1) to produce new genetic data from Crithidia bombi, C. mellificae and Lotmaria passim isolated from honeybees and bumblebees. These were analysed by applying population genetic tools in order to quantify and compare their variability within and between species, and to obtain information on their demography and population structure. The general pattern for the three species was that they were subject to the action of purifying selection on nonsynonymous variants, the levels of within species diversity were similar irrespective of the host, there was evidence of recombination among haplotypes and they showed no haplotype structuring according to the host. C. bombi exhibited the lowest levels of synonymous variation (πS= 0.06 ± 0.04%) — and a mutation frequency distribution compatible with a population expansion after a bottleneck — that contrasted with the extensive polymorphism displayed by C. mellificae (πS= 2.24 ± 1.00 %), which likely has a more ancient origin. L. passim showed intermediate values (πS= 0.40 ± 0.28 %) and an excess of variants a low frequencies probably linked to the spread of this species to new geographical areas.eng© 2021 by the authors. This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article's Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article's Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http://creativecommons.org/licenses/by/4.0/Atribución 4.0 Internacionalhttp://creativecommons.org/licenses/by/4.0/Population geneticsGenetic diversityPopulation structureLotmaria passimCrithidia mellificaeCrithidia bombijournal article10.1007/s00248-021-01882-w1432-184Xopen access