Spread of a New Parasitic B Chromosome Variant Is Facilitated by High Gene Flow Manrique-Poyato, María Inmaculada López León, María Dolores Cabrero, Josefa Perfectti Álvarez, Francisco Martínez Camacho, Juan Pedro Chromosomes Evolutionary genetics Gene flow Genome evolution Grasshoppers Parasite evolution Sequence analysis Suppressor genes The B24 chromosome variant emerged several decades ago in a Spanish population of the grasshopper Eyprepocnemis plorans and is currently reaching adjacent populations. Here we report, for the first time, how a parasitic B chromosome (a strictly vertically transmitted parasite) expands its geographical range aided by high gene flow in the host species. For six years we analyzed B frequency in several populations to the east and west of the original population and found extensive spatial variation, but only a slight temporal trend. The highest B24 frequency was found in its original population (Torrox) and it decreased closer to both the eastern and the western populations. The analysis of Inter Simple Sequence Repeat (ISSR) markers showed the existence of a low but significant degree of population subdivision, as well as significant isolation by distance (IBD). Pairwise Nem estimates suggested the existence of high gene flow between the four populations located in the Torrox area, with higher values towards the east. No significant barriers to gene flow were found among these four populations, and we conclude that high gene flow is facilitating B24 diffusion both eastward and westward, with minor role for B24 drive due to the arrival of drive suppressor genes which are also frequent in the donor population. 2014-03-25T11:40:01Z 2014-03-25T11:40:01Z 2013 journal article Manrique-Poyato, M.I.; et al. Spread of a New Parasitic B Chromosome Variant Is Facilitated by High Gene Flow. Plos One, 8(12): e83712 (2013). [http://hdl.handle.net/10481/31089] 1932-6203 http://hdl.handle.net/10481/31089 eng http://creativecommons.org/licenses/by-nc-nd/3.0/ open access Creative Commons Attribution-NonCommercial-NoDerivs 3.0 License Public Library of Science (PLOS)