In the past two decades, researchers have shown that biological traits in both species and individual cells can be shaped by the environment and inherited even without gene mutations, an outcome that contradicts one of the classical interpretations of Darwinian theory. But exactly how these epigenetic, or non-genetic, traits are inherited has been unclear. Now, in a study published Oct. 27 in the journal Cell Reports, Yale scientists show how epigenetic mechanisms contribute in real time to the evolution of a gene network in yeast. Specifically, through multiple generations yeast cells were found to pass on changes in gene activity induced by researchers. The finding helps shed light on a longstanding question in evolutionary biology; scientists have long debated whether organisms can pass on traits acquired during a lifetime.
“Do genetic mutations have to be the sole facilitator of gene network evolution or can epigenetic mechanisms also lead to stable and heritable gene expression states maintained generation after generation?” asked Yale’s Murat Acar, associate professor of molecular, cellular & developmental biology, a faculty member at the Yale Systems Biology Institute, and senior author of the paper. During much of the last half of the 20th century, biology students were taught that mutations of genes that helped species adapt to the environment were passed on through generations, eventually leading to tremendous diversity of life. However, this theory had a problem: advantageous mutations are rare, and it would take many generations for physiological changes caused by the mutation to take root in a population of any given species.