Epigenetic Inheritance: A Contributor to Species Differentiation?

Abstract

Multiple epigenetic states can be associated with the same genome, and transmitted through the germline for generations, to create the phenomenon of epigenetic inheritance. This form of inheritance is mediated by complex and highly diverse components of the chromosome that associate with DNA, control its transcription, and are inherited alongside it. But, how extensive, and how stable, is the information carried in the germline by the epigenome? Several known examples of epigenetic inheritance demonstrate that it has the ability to create selectable traits, and thus to mediate Darwinian evolution. Here we discuss the possibility that epigenetic inheritance is responsible for some stable characteristics of species, focusing on a recent comparison of the human and chimpanzee methylomes which reveals that somatic methylation states are related to methylation states in the germline. Interpretation of this finding highlights the potential significance of germline epigenetic states, as well as the challenge of investigating a form of inheritance with complex and unfamiliar rules.

Is animal research sufficiently evidence based to be a cornerstone of biomedical research?

“…25 Others argue that animal models will always fail to predict human outcomes reliably because humans and animals are such complex interactive systems with different evolutionary trajectories that even small differences between species could be important. 36 The genomic and inherent differences between rodent and human physiology are increasingly acknowledged, 37 and even non-human primates have many differences in the epigenome that fundamentally affect the functionality of the genome 38 and may account for their lack of success in predicting clinical response. [39][40][41] Even if the research was conducted faultlessly, animal models might still have limited success in predicting human responses to drugs and disease because of inherent inter-species differences in molecular and metabolic pathways.…”

Methylomes

“…The methylation states that present in the germline are heritable and participate in evolution. Boffelli D and Martin DI [6] combined phylogenomic and somatic methylation data to infer germline methylation states. Methylated CGs undergo mutation to TG much more frequently than unmethylated CGs, but only CG decay that occurs in the germline results in heritable sequence changes that can become fixed within a species.…”

“…From a functional perspective, the DNA methylome variation is a stable change in a transcriptional regulatory element, which changes the expression of a gene without any change in DNA sequence or in the intracellular environment. However, a change in environmental conditions could perturb the stability profile of the methylome at a locus, changing the probability of variant states arising, even making a variant state more stable than the previous reference state [6].…”

Natural epigenetic variation in bats and its role in evolution

“…Although they could establish the correlation between epigenetic and phenotypic variation effectively, they may not reflect the epigenetic features in the real world. The interaction between epigenetic processes and natural environments may be more complex, and epigenetic processes may take part in advanced physiological processes such as botanic hybridization and polyploidization (Ellstrand and Schierenbeck, 2000; Liu and Wendel, 2003;Rapp and Wendel, 2005;Salmon et al, 2005), and ecological niche differentiation (Herrera et al, 2012;, and thus may even cause speciation (Boffelli and Martin, 2012;Flatscher et al, 2012). Thus, it is important to investigate epigenetic variation and epigenetic inheritance and estimate the potential role of epigenetic variation in producing new phenotypes and responding to global environmental change in natural populations (Bossdorf et al, 2008; Ledón-Rettig, 2013 Variations in natural genomic methylation have been investigated in populations of several plant species.…”