Wild populations of the marine Threespine stickleback could evolve a tolerance to colder water temperatures than they currently experience, according to new research from the University of British Columbia.
Such rapid evolution is considered important with the continuing threat of global warming, which is expected to bring with it a greater variability in temperatures.
Gasterosteus aculeatus exist in both marine and freshwater habitats, albeit that they have evolved separately, particularly morphologically with freshwater sticklebacks having far fewer armour plates than their marine ancestors.
Tests were conducted on wild and lab-raised sticklebacks (marine and freshwater), the results of which showed that freshwater sticklebacks were more cold-tolerant than their marine counterparts.
This was to be expected, given that freshwater lakes in British Columbia reach colder temperatures than the sea during the winter.
To discover how quickly the adaptation could take place, lead author Rowan Barrett and his team, transplanted wild marine sticklebacks from Oyster Lagoon, British Columbia to freshwater experimental ponds of 23m x 23m x 3m (max. depth).
Cold tolerance in three generations
During the course of only three generations, or three years, the resultant offspring of the marine sticklebacks showed a greater tolerance to cold temperatures than their ancestors, as much as 2.5 °C colder, such a rate of phenotypic evolution is considered to be among the most rapid that has been observed in a natural population.
Barrett says in the paper: “The ability to tolerate increasingly severe temperature extremes will be crucial for species to adapt to the greater variability in temperature expected from climate change.
"It remains to be seen whether stickleback populations living in locations with environmental temperatures closer to their maximum heat tolerance will be capable of adapting to shifts towards warmer temperatures.
"Moreover, it is not clear whether other species of freshwater fish possess sufficient heritable genetic variation to permit rapid evolutionary change in temperature tolerance."
For more information see the paper: Rowan D. H. Barrett, Antoine Paccard, Timothy M. Healy, Sara Bergek, Patricia M. Schulte, Dolph Schluter and Sean M. Rogers (2010) - Rapid evolution of cold tolerance in stickleback Proc. R. Soc. B published online 4 August 2010
doi: 10.1098/rspb.2010.0923