Evolution in real-time — the case of threespine stickleback fish in Stanley Park, British Columbia
We often think of evolution as something that requires many human lifetimes to occur, and it is therefore difficult to find examples of vertebrate evolution that can be directly studied as they occur in nature.
Sometimes, however, these changes can happen very quickly, and here we study this phenomenon in a population of threespine stickleback fish that were trapped in Lost Lagoon, a small freshwater pond created from a marine inlet in Stanley Park in downtown Vancouver, BC in 1930.
Read this open access paper on the FACETS website.
These small fish, found in coastal habitats across the northern hemisphere, are known to evolve a reduced number of armour plates on their bodies, along with various other body shape changes, when they transition from their ancestral marine habitats into freshwater.
We used computed tomography to study the skeletons of these fish, and genotyping tools to characterize a key gene associated with freshwater-related changes.
Our results show that the fish in this pond have diverged somewhat in shape from their marine ancestors, but are still quite different from fish from other local freshwater ponds. Interestingly, however, they have lost a large number of armour plates, and their genotypes and armour plate profiles are closer than their body shapes are to what we see in fully freshwater fish.
Our results imply that the Lost Lagoon population is in the process of undergoing this evolutionary transition, and is at an intermediate point along a trajectory toward a freshwater body type. Our results also show that these changes are occurring on a contemporary timescale, and this may have implications for our understanding of how animals respond to rapidly changing environmental conditions.
Threespine stickleback are an important prey species on the Canadian west coast, and understanding their responses to climate change may help us make better conservation decisions in relation to Canada’s coastal ecosystems.
Read the paper — Characterizing contemporary evolutionary change in a recently isolated population of threespine stickleback (Gasterosteus aculeatus L.) by Aspen M. Kozak, Tegan N. Barry, Brenna C.M. Stanford, Sean M. Rogers, and Heather A. Jamniczky.
