Genetic tropicalisation following a marine heatwave

Melinda A. Coleman, Antoine J.P. Minne, Sofie Vranken, Thomas Wernberg

Research output: Contribution to journalArticlepeer-review

37 Citations (Scopus)


Extreme events are increasing globally with devastating ecological consequences, but the impacts on underlying genetic diversity and structure are often cryptic and poorly understood, hindering assessment of adaptive capacity and ecosystem vulnerability to future change. Using very rare “before” data we empirically demonstrate that an extreme marine heatwave caused a significant poleward shift in genetic clusters of kelp forests whereby alleles characteristic of cool water were replaced by those that predominated in warm water across 200 km of coastline. This “genetic tropicalisation” was facilitated by significant mortality of kelp and other co-occurring seaweeds within the footprint of the heatwave that opened space for rapid local proliferation of surviving kelp genotypes or dispersal and recruitment of spores from warmer waters. Genetic diversity declined and inbreeding increased in the newly tropicalised site, but these metrics were relative stable elsewhere within the footprint of the heatwave. Thus, extreme events such as marine heatwaves not only lead to significant mortality and population loss but can also drive significant genetic change in natural populations.

Original languageEnglish
Article number12726
JournalScientific Reports
Issue number1
Publication statusPublished - 1 Dec 2020


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