The Rohner lab is interested in all the endless beautiful variation we can observe in the animal kingdom. Specifically we are interested in how animals can adapt to extreme environments by investigating the general genetic mechanisms and particular mutations underlying this adaptation.
Understanding the genetic basis of adaptation has broad applications not only for a basic understanding of evolution but also for human pathologies given that many modern human diseases (e.g. diabetes, allergies, many types of cancer) are a consequence of being mis-adapted to modern society.
We are mostly using the cavefish system Astyanax mexicanus as a model system to address the genetic basis of adaptation because of its clear ecological adaptation scenario, its multiple interfertile populations and the ability to breed and live in the laboratory.
The cavefish Astyanax mexicanus is an exciting model organism that provides us with a clear ecological adaptation scenario, the adaptation to the subterranean cave environment. The model is perfect to study the combination of environment and the resulting variation, given the direction of evolution and adaptation is known (from surface to cave) and the environment of the cave provides reasonably well defined environmental parameters such as the lack of light, the scarcity of food, and the absence of predators. Most importantly the ancestral surface form remains interfertile with the cave populations, allowing for genetic (e.g. Quantitative Trait Loci - QTL) and developmental studies.
Additionally, there are numerous independently evolved cave populations (e.g. Tinaja, Pachon, Molino) that have converged on the cave-morph phenotype, each of which is the result of a replicated natural experiment, making it an ideal system to study parallelism and convergence.
Our current main focus in the lab is to study the genetic basis of metabolic adaptation. Among the biggest challenges for animals in a cave environment is the scarcity of food. Since caves are completely dark, no primary photosynthetic producers can survive in this extreme environment. Therefore, cavefish depend from food sources outside of the caves, mostly input from bats and seasonal flooding. Given the unpredictability of such food sources, cavefish have adapted to long starvation periods and optimized their metabolism accordingly.
For example, cavefish have increased their appetite, enlarged fat reservoirs, and altered fat and lipid deposition. Despite these impressive changes to their metabolism, cavefish remain healthy, fertile and do not show any sign of distress, even when fed high fat diets.
In a recent study we found that cavefish are showing phenotypes that are usually associated with diabetes patients, such as high blood sugar, glucose intolerance and insulin resistance. But in contrast to humans, cavefish are using these phenotypes to grow faster and and gain more weight. As such they presumably have found strategies to circumvent the typically negative consequences associated with these phenotypes. As a matter of fact we found common markers of diabetes such as inflammation and glycation end products to be reduced in cavefish.
Check out here our latest paper on bioRxiv.
We are aiming to study the genetic basis of these physiological alterations in order to understand adaptation to nutrient poor environments with the ultimate goal of finding ways to counteract our own health problems which arise as a consequence of living under conditions we are not adapted to.
Our custom built state-of-the-art Pentair systems (10 racks) are individually monitored and controlled to ensure the best health, growth and breeding success of several thousand cavefish.
Cavefish display many phenotypes usually associated with metabolic syndrome, such as larger amount of visceral fat and insulin resistance as part of their strategy to survive under limited nutrient availability in the cave environment. Interestingly, these phenotypes, however, do not lead to health problems in cavefish.
Feel free to email us if you have any questions about our cavefish research or current openings in the Rohner Lab.
The Rohner Lab in the Pachón cave during a field trip in 2017.
Postdoctoral Research Associate
Postdoctoral Research Associate
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