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Dryad

Rapid genome-wide purging following tsunami-induced hybridization

Abstract

Catastrophic disasters can impact biodiversity by disturbing habitats. However, such events are so rare and unpredictable that we have few opportunities to directly observe how biodiversity is lost or restored immediately after catastrophic events. On March 11, 2011, a devastating tsunami hit the Tohoku Region, Japan, creating new habitats and inducing hybridization between freshwater Gasterosteus aculeatus and marine G. nipponicus sticklebacks. Our 9-year continuous monitoring revealed that G. nipponicus alleles were purged at major loci responsible for reproductive isolation, including ancestral-X and neo-X chromosomes, within the first few generations after hybridization. Subsequently, G. nipponicus alleles were purged across the entire genome except at several loci. Semipermeable yet robust species barriers can therefore rapidly purge heterospecific genomes within ten generations and maintain species identity after hybridization.