Environmental Heterogeneity and Phenotypic Divergence: Can Heritable Epigenetic Variation Aid Speciation?

Abstract

The dualism of genetic predisposition and environmental influences, their interactions, and respective roles in shaping the phenotype have been a hot topic in biological sciences for more than two centuries. Heritable epigenetic variation mediates between relatively slowly accumulating mutations in the DNA sequence and ephemeral adaptive responses to stress, thereby providing mechanisms for achieving stable, but potentially rapidly evolving phenotypic diversity as a response to environmental stimuli. This suggests that heritable epigenetic signals can play an important role in evolutionary processes, but so far this hypothesis has not been rigorously tested. A promising new area of research focuses on the interaction between the different molecular levels that produce phenotypic variation in wild, closely-related taxa that lack genome-wide genetic differentiation. By pinpointing specific adaptive traits and investigating the mechanisms responsible for phenotypic differentiation, such study systems could allow profound insights into the role of epigenetics in the evolution and stabilization of phenotypic discontinuities, and could add to our understanding of adaptive strategies to diverse environmental conditions and their dynamics.

Epigenetic Differentiation Persists after Male Gametogenesis in Natural Populations of the Perennial Herb Helleborus foetidus (Ranunculaceae)

“…In close parallel with its long-acknowledged role in facilitating the transmission of somatic cell mutations to gametes [61], [62], late developmental appearance of germline in plants will also facilitate the transmission of epigenetic marks in nuclear DNA from somatic cells to gametes. Apart from its potential evolutionary significance [6], [23], [31], this circumstance opens practical opportunities for epigenetic research on natural plant populations, as illustrated by this study. Mature pollen grains are either bi- or trinucleate (binucleate in H. foetidus ; [63]), containing one vegetative cell and one or two sperm cells.…”

“…The current lack of information on the transgenerational constancy of epigenetic characteristics of wild plant populations in natural scenarios has so far hindered interpretations of natural patterns of epigenetic variation in an evolutionary framework [20], [28]. This particularly applies to instances of epigenetic differentiation between populations of the same species living in contrasting environments [14], [15], [29], [30], whose evolutionary significance will critically depend on whether such potentially adaptive, epigenetic structuring persist across successive generations [4], [20], [31]. Evaluating transgenerational constancy of standing epigenetic structuring in wild plant populations, however, confronts some difficulties.…”

MSAP markers and global cytosine methylation in plants: a literature survey and comparative analysis for a wild‐growing species

“…These findings highlight the potential of this genomic feature for gaining a better understanding of the implications of DNA methylation at both intra‐ and interspecific scales (Flatscher et al . ; Richards et al . ; Alonso et al .…”

Epigenetics and the Evolution of Darwin’s Finches

“…It is conceivable that epigenetic changes may also accumulate over longer periods of evolutionary time, contributing to processes such as adaptive radiation (Rebollo et al 2010; Flatscher et al 2012). This hypothesis assumes that epigenetic changes persist over thousands of generations.…”