Despite that the field of epigenetics is often dismissed as a fad topic, that may come back to surprise us, just as the derision of ‘junk DNA’ did several decades ago.
Similar to the silver fox domestication project, scientists in Sweden replicated domestication of red jungle fowl (ancestors of modern chickens) and selected for fear of humans tameness. After five generations, they examined changes in the genetic structure associated with certain phenotypic traits, especially behavior.
Behavioral traits are associated with many physiological and neural mechanisms. Signaling compounds in the body involved with these processes are dopamine, glucocorticoids, epinephrine, and many others. All of these signaling molecules are synthesized in tissues and organs, such as they hypothalamus. Based on prior studies, the research team examined changes in the hypothalamus of their test subjects. They discovered that not only were DNA methylation patterns associated with cellular metabolism and neural signaling, but there were sex-specific changes.
In agreement with other similar studies of selection pressure during domestication, this study adds further evidence that changes in genetic structure are related to the driver(s) of selection for specific traits, such as egg size in a breed of domesticated chickens.
“This suggests that different selection pressures generate distinctive sets of epigenetic changes, which in turn are related to specific phenotypic traits.”Epigenetics may have increasing importance now because of its suggestive role in phenotypic plasticity, which often precedes adaptation to environmental change. Understanding how organisms respond to selection pressure can help us better model and predict the fates of many species of concern in this age of rapid climate and anthropogenic changes. Including our own.
“Our results suggest that bidirectional selection for tameness involves epigenetic factors that can even differ in a sex-specific manner. Observation of divergent DNA methylation patterns in the hypothalamus after only five generations of artificial selection highlights the importance of epigenetic mechanisms, in addition to genetic composition, in evolutionary phenotypic variation that emerges in response to selection pressures.”A researcher in Europe has been studying these association based on changes in gene expression in melanin, phenotype, and behavior adaptation in owls. Ironically, humans have unknowingly been experimenting in this for thousands of years by our own selection for domestication of many plant and animal species.
