A population study of Phytophthora cactorum was performed using ddRADseq sequence variation analysis completed by the analysis of effector genes-RXLR6, RXLR7 and SCR113. The population structure was described by F-statistics, heterozygosity, nucleotide diversity, number of private alleles, number of polymorphic sites, kinship coefficient and structure analysis. The population of P. cactorum in Europe seems to be structured into host-associated groups. The isolates from woody hosts are structured into four groups described previously, while isolates from strawberry form another group. The groups are diverse in effector gene composition and the frequency of outbreeding. When populations from strawberry were analysed, both asexual reproduction and occasional outbreeding confirmed by gene flow among distinct populations were detected. Therefore, distinct P. cactorum populations differ in the level of heterozygosity. The data support the theory of the mixed-mating model for P. cactorum, comprising frequent asexual behaviour and inbreeding alternating with occasional outbreeding. Because P. cactorum is not indigenous to Europe, such variability is probably caused by multiple introductions of different lineages from the area of its original distribution, and the different histories of sexual recombination and host adaptation of particular populations.

• Keywords
• Phytophthora cactorum, effector genes, mixed-mating system, population structure, reproduction,
• Publication type
• Journal Article MeSH

The mammalian major histocompatibility complex (MHC) is a tightly linked cluster of immune genes, and is often thought of as inherited as a unit. This has led to the hope that studying a single MHC gene will reveal patterns of evolution representative of the MHC as a whole. In this study we analyse a 1000-km transect of MHC variation traversing the European house mouse hybrid zone to compare signals of selection and patterns of diversification at two closely linked MHC class II genes, H-2Aa and H-2Eb. We show that although they are 0.01 cM apart (that is, recombination is expected only once in 10 000 meioses), disparate evolutionary patterns were detected. H-2Aa shows higher allelic polymorphism, faster allelic turnover due to higher mutation rates, stronger positive selection at antigen-binding sites and higher population structuring than H-2Eb. H-2Eb alleles are maintained in the gene pool for longer, including over separation of the subspecies, some H-2Eb alleles are positively and others negatively selected and some of the alleles are not expressed. We conclude that studies on MHC genes in wild-living vertebrates can give substantially different results depending on the MHC gene examined and that the level of polymorphism in a related species is a poor criterion for gene choice.

• MeSH
• Alleles * MeSH
• DNA Primers genetics   MeSH
• Phylogeny MeSH
• Genetic Variation * MeSH
• Gene Components MeSH
• Major Histocompatibility Complex genetics   MeSH
• Hybridization, Genetic * MeSH
• Models, Genetic MeSH
• Evolution, Molecular * MeSH
• Molecular Sequence Data MeSH
• Mice genetics   MeSH
• Genetics, Population MeSH
• Amino Acid Sequence MeSH
• Base Sequence MeSH
• Sequence Alignment MeSH
• Selection, Genetic * MeSH
• Cluster Analysis MeSH
• Animals MeSH
• Check Tag
• Mice genetics   MeSH
• Animals MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH
• Comparative Study MeSH
• Names of Substances
• DNA Primers MeSH