Variable opportunities for outcrossing result in hotspots of novel genetic variation in a pathogen metapopulation: Spatially variable opportunities for outcrossing in an obligate pathogen

Research output: Contribution to journalArticleScientificpeer-review


  • Anna Liisa Laine
  • Benoit Barrès
  • Elina Numminen
  • Jukka Siren

Research units

  • University of Helsinki
  • Universitat Zurich
  • Université de Lyon
  • Research Centre for Ecological Change


Many pathogens possess the capacity for sex through outcrossing, despite being able to reproduce also asexually and/or via selfing. Given that sex is assumed to come at a cost, these mixed reproductive strategies typical of pathogens have remained puzzling. While the ecological and evolutionary benefits of outcrossing are theoretically well-supported, support for such benefits in pathogen populations are still scarce. Here, we analyze the epidemiology and genetic structure of natural populations of an obligate fungal pathogen, Podosphaera plantaginis. We find that the opportunities for outcrossing vary spatially. Populations supporting high levels of coinfection –a prerequisite of sex – result in hotspots of novel genetic diversity. Pathogen populations supporting coinfection also have a higher probability of surviving winter. Jointly our results show that outcrossing has direct epidemiological consequences as well as a major impact on pathogen population genetic diversity, thereby providing evidence of ecological and evolutionary benefits of outcrossing in pathogens.


Original languageEnglish
Publication statusPublished - 1 Jun 2019
MoE publication typeA1 Journal article-refereed

    Research areas

  • Cost of sex, Diversity, Epidemiology, Outcrossing, Overwintering

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ID: 37052537