Epigenetics as a source of variation in comparative animal physiology – or – Lamarck is lookin' pretty good these days

Abstract

Considerable variation is inherent both within and between comparative physiological data sets. Known sources for such variation include diet, gender, time of day and season of experiment, among many other factors, but a meta-analysis of physiological studies shows that surprisingly few studies report controlling for these factors. In fact, less than 3% of comparative physiological papers mention epigenetics. However, our understanding of epigenetic influences on physiological processes is growing rapidly, and it is highly likely that epigenetic phenomena are an additional 'hidden' source of variation, particularly in wild-caught specimens. Recent studies have shown epigenetic inheritance of commonly studied traits such as metabolic rate (water fleas Daphnia magna; emu, Dromaius novaellandiae), hypoxic tolerance, cardiac performance (zebrafish, Danio rerio), as well as numerous morphological effects. The ecological and evolutionary significance of such epigenetic inheritance is discussed in a comparative physiological context. Finally, against this context of epigenetic inheritance of phenotype, this essay also provides a number of caveats and warnings regarding the interpretation of transgenerational phenotype modification as a true epigenetic phenomenon. Parental effects, sperm storage, multiple paternity and direct gamete exposure can all be confounding factors. Epigenetic inheritance may best be studied in animal models that can be maintained in the laboratory over multiple generations, to yield parental stock that themselves are free of epigenetic effects from the historical experiences of their parents.

Deepwater Horizon Oil Spill as a Case Study for Interdisciplinary Cooperation within Developmental Biology, Environmental Sciences and Physiology

“…Moreover, some of these multigenerational effects can be either "washed in" (not appearing until the F2 generation) or "washed out" by slowly dissipating over 2 -3 generations rather than suddenly disappearing (Figure 3). These findings lend empirical evidence for predicted complex epigenetic dynamics ( [106] [107]). …”

Ecological Epigenetics in Marine Metazoans

“…Within the "genome to phenome" pathway, epigenomic processes alter the manner in which DNA is transcribed into mRNA without altering DNA sequence, and thus contributes to physiological plasticity of the organism in an intergenerational or intragenerational context (Burggren, 2014(Burggren, , 2015. In general, ecological epigenomics is under-studied in marine systems.…”

The expanding epigenetic landscape of non-model organisms

“…Its use for epigenetic research has been advocated before (Burggren, 2014;Harris et al, 2012) but a Daphnia genome was sequenced only recently (Colbourne et al, 2011), marking the entry of this organism into the arena of molecular epigenetic research. The key aspects of Daphnia biology that make it valuable to epigeneticists are its ability to reproduce both sexually and asexually and the fact that parthenogenetic individuals, which are genetic clones of the mother, can nonetheless display diverse phenotypes depending on their exposure to certain stimuli during development.…”