Japan's 2011 tsunami sparked fish hybridization, but species boundaries largely held
How are species boundaries maintained in the face of environmental disturbance? This is not only a fundamental question in evolutionary biology but also an increasingly important one as human activities and climate change alter habitats and bring previously separated species into contact.
The 2011 tsunami in Japan brought together the marine Japan Sea stickleback (Gasterosteus nipponicus) and a freshwater population of the threespine stickleback (Gasterosteus aculeatus) in Otsuchi Town. This led to interspecific hybridization, which the research team tracked for nine years. Initially, 38% of the sampled individuals were hybrids in 2012, but over time, genomic regions derived from G. nipponicus rapidly declined, and by 2020, the population had returned to an almost entirely G. aculeatus genomic composition.
This occurred within about 10 generations, with major loci associated with freshwater adaptation, migration to the sea, mate choice, and hybrid male sterility showing particularly rapid declines. However, individual-based simulations suggested that numerous weak genetic incompatibilities distributed throughout the genome may also have contributed to the rapid elimination of G. nipponicus ancestry.
Brief written by urgent.news from Phys.org's own syndicated text. Machine-written — may contain errors; check the original before relying on it.
