The inheritance of environmentally-induced traits (an important part of the Lamarckian theory of evolution) was dismissed by 20th Century evolutionary biologists. However, recent studies support that environmentally induced phenotypes can persist for several generations via epigenetic mechanisms. It is suggested that germ line mediated inheritance of epigenetic variation might underlie the basis for rapid and directional adaptations to specific environments. At the end, germ line epigenetic variation should be assimilated in the genome through a process of epigenetically-driven genetic variation. Currently, this possibility has not been demonstrated in mammals.
Here we will test this hypothesis. We previously exposed isogenic mice to a nutritional challenge (excess calorie intake) for 3 consecutive generations. The exposed mice developed overweight and obesity. Strikingly, the metabolic phenotypes were stably inherited for 3 additional generations in the absence of the trigger. Such rapid and stable transmission of phenotypes can be explained by genetic assimilation after germ line epigenetic changes are generated.
Here, we will map epigenetic variation (DNA methylation, non-coding RNAs) in germ cells, and study whether they lead to de novo DNA variation (mutations).