Aotearoa New Zealand whitebait can rapidly switch their life-cycles in response to sudden environmental changes, new University of Otago – Ōtākou Whakaihu Waka research shows.
The fish – which go to sea as juveniles in autumn and migrate back into rivers during spring, where they are caught as whitebait – undergo dramatic biological shifts when their paths to the sea become blocked.
Professor Jonathan Waters
Senior author Professor Jonathan Waters, of the Department of Zoology, says this can occur after significant events, such as earthquakes.
“In New Zealand, earthquakes have caused major landslides, which have formed new lakes and prevented whitebait from going to sea,” he says.
“Our research shows that whitebait isolated in lakes can rapidly swap their life-cycles, so they are breeding in spring instead of autumn, to take advantage of increased lake productivity over the summer.”
Co-author Professor Gerry Closs, also of the Department of Zoology, says whitebait that live solely in lakes have evolved to become smaller and weaker than marine whitebait, which need to be strong swimmers in rough coastal waters.
“Interestingly, our research shows that sea-going whitebait are far more muscular and fast-growing than landlocked whitebait, which may have relevance for future whitebait aquaculture,” Professor Closs says
Published in the journal Nature Communications, the study compared the genetics of landlocked whitebait with migratory whitebait and found that some of the sea-going fish are “jackpot” individuals carrying the ability to adapt to landlocking.
Lead author Ash Iwikau, Master of Science student in the Department of Zoology, says the researchers found a small part of the whitebait genome which is crucial for adapting to lake conditions.
“It’s almost as though the fish are pre-adapted to cope with environmental change,” she says.
“This research provides unique insights into how genomes can be structured to enable animals to keep pace with ecological change.”
Publication:
Migratory jackpot individuals fuel rapid ecotype shifts in Galaxias fishes
Ashleigh Iwikau, Jason Augspurger, Marc A. Bailie, Graham A. McCulloch, Mitra M. Darestani, Tania M. King, Gerard P. Closs, Travis Ingram, P. Mark Lokman, Bruce Deagle, Christopher P. Burridge, Ludovic Dutoit & Jonathan M. Waters
