Can epigenetics translate environmental cues into phenotypes?

Living organisms are constantly exposed to wide ranges of environmental cues. They react to these cues by undergoing a battery of phenotypic responses, such as by altering their physiological and behavioral traits, in order to adapt and survive in the changed environments. The adaptive response of a species induced by environmental cues is typically thought to be associated with its genetic diversity such that higher genetic diversity provides increased adaptive potential. This originates from the general consensus that phenotypic traits have a genetic basis and are subject to Darwinian natural selection and Mendelian inheritance. There is no doubt about the validity of these principles, supported by the successful introgression of specific traits during (selective) breeding. However, a range of recent studies provided fascinating evidences suggesting that environmental effects experienced by an organism during its lifetime can have marked influences on its phenotype, and additionally the organism can pass on the acquired phenotypes to its subsequent generations through non-genetic mechanisms (also termed as epigenetic mechanism) - a notion that dates back to Lamarck and has been controversial ever since. In this review, we describe how the epigenetics has reshaped our long perception about the inheritance/development of phenotypes within organisms, contrasting with the classical gene-based view of inheritance. We particularly highlighted recent developments in our understanding of inheritance of parental environmental induced phenotypic traits in multicellular organisms under different environmental conditions, and discuss how modifications of the epigenome contribute to the determination of the adult phenotype of future generations.