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Long-term spatio-temporal genetic structure of an accidental parasitoid introduction, and local changes in prevalence of its associated Wolbachia symbiont
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  • Anne Duplouy,
  • Abhilash Nair,
  • Toshka Nyman,
  • Saskya van Nouhuys
Anne Duplouy
University of Helsinki

Corresponding Author:[email protected]

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Abhilash Nair
University of Helsinki
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Toshka Nyman
University of Helsinki
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Saskya van Nouhuys
Cornell University
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Population bottlenecks associated with founder events strongly impact the establishment and genetic makeup of populations. In addition to their genotype, founding individuals also bring along symbionts that can manipulate the phenotype of their host, affecting the host population establishment, dynamics and evolution. Thus, to understand introduction, invasion, and spread, we should identify the roles played by accompanying symbionts. In 1991, the parasitoid wasp, Hyposoter horticola, and its associated hyperparasitoid were accidentally introduced from the main Åland islands, Finland, to an isolated island in the archipelago, along with their host, the Glanville fritillary butterfly. Though the receiving island was unoccupied, the butterfly was present on some of the small islands in the vicinity. The three species have persisted as small populations ever since. A strain of the endosymbiotic bacterium Wolbachia has an intermediate prevalence in the H. horticola across the main Åland population. The infection increases susceptibility of the parasitoid to hyperparasitism. We investigated the establishment and spread of the parasitoid, along with patterns of prevalence of its symbiont using 323 specimens collected between 1992 and 2013, from five localities across Åland, including the source and introduced populations. Using 14 microsatellites and one mitochondrial marker, we suggest that the relatively diverse founding population and occasional migration between islands might have facilitated the persistence of all isolated populations, despite multiple local population crashes. We also show local near-fixation of Wolbachia, where the hyperparasitoid is absent, and selection against infected wasp genotypes is relaxed.
23 Mar 2021Submitted to Molecular Ecology
23 Mar 2021Reviewer(s) Assigned
28 May 2021Review(s) Completed, Editorial Evaluation Pending
02 Jun 2021Editorial Decision: Revise Minor
14 Jun 2021Review(s) Completed, Editorial Evaluation Pending
14 Jun 20211st Revision Received
02 Jul 2021Editorial Decision: Accept