Zebrafish have been used in medical research since at least the 1970’s as their anatomy, physiology, as well as genetics are similar to humans. Other advantages to studying zebrafish is that they are inexpensive to raise, and they reproduce well in captivity.
The ability to adjust one’s physiology in response to varying environments is called plasticity. An organism may encounter any number of environmental fluctuations (light/dark, temperatures, predation risk, noise, etc) throughout course of a day, week, month, year, and so on. Plasticity is therefore very important for an animal’s survival and success. After an estimated 150 generations, by some accounts, zebrafish offer a unique opportunity to examine how domestication may have changed the physiology of captive-raised fish who are exposed to fairly consistent environmental conditions (about 28 degrees C, human interactions, dependable food, aquarium-mates) in comparison to wild zebrafish.
So, what happens when you take a laboratory-raised zebrafish that is used to such posh conditions, and adjust the thermostat to mirror fluctuations a fish might experience in the wild (10-38 degrees C)? This is precisely what a new study published in the Proceedings of the National Academy of Science examined. They found that young laboratory fish had reduced plasticity in comparison to young wild zebrafish. In other words, because the lab-raised fish had such predictable environments, they lost the ability to adjust their physiology when the environment changed. I guess that supports the old idiom, “use it or lose it.” The wild fish, on the other hand, were able to adapt to changing temperatures more readily.
These findings suggest that there is a physiological cost to being flexible such that some domesticated animals may lose their plasticity.
R Morgan, AH Andreassen, ER Åsheim, MH Finnøen, G Dresler, T Brembu, A Loh, JJ Miest, F Jutfelt. Reduced physiological plasticity in a fish adapted to stable temperatures. Proceedings of the National Academy of Sciences. 119(22), e2201919119. https://doi.org/10.1073/pnas.2201919119