Abstract
The hypothesis that epigenetic mechanisms of gene expression regulation have two main roles in vertebrate sex is presented. First, and within a given generation, by contributing to the acquisition and maintenance of (i) the male or female function once during the lifetime in individuals of gonochoristic species; and (ii) the male and female function in the same individual, either at the same time in simultaneous hermaphrodites, or first as one sex and then as the other in sequential hermaphrodites. Second, if environmental conditions change, epigenetic mechanisms may have also a role across generations, by providing the necessary phenotypic plasticity to facilitate the transition: (i) from one sexual system to another, or (ii) from one sex-determining mechanism to another. Furthermore, if the environmental change lasts enough time, epimutations could facilitate assimilation into genetic changes that stabilize the new sexual system or sex-determining mechanism. Examples supporting these assertions are presented, caveats or difficulties and knowledge gaps identified, and possible ways to test this hypothesis suggested.This article is part of the theme issue ‘Challenging the paradigm in sex chromosome evolution: empirical and theoretical insights with a focus on vertebrates (Part I)’.
Highlights
To explain how epigenetics can contribute to sex determination and to the evolutionary transitions between different sexual systems, first it is necessary to briefly define some terms used throughout the text, as hermaphroditism, one of several types of sexual systems, has been regarded as epigenetic sex determination (e.g. [1])
The idea that epigenetics participates in the evolutionary transitions between different sexual systems and between different sexdetermining mechanisms will be discussed
Dmrt1 is involved in sex determination [36]. These results provide evidence of a common mechanism regulating genotypic sex determination (GSD) and environmental sex determination (ESD) and their coexistence in the same species
Summary
Institut de Ciències del Mar (ICM), Spanish National Research Council (CSIC), Passeig Marítim, 37-49, 08003 Barcelona, Spain. The hypothesis that epigenetic mechanisms of gene expression regulation have two main roles in vertebrate sex is presented. If environmental conditions change, epigenetic mechanisms may have a role across generations, by providing the necessary phenotypic plasticity to facilitate the transition: (i) from one sexual system to another, or (ii) from one sex-determining mechanism to another. If the environmental change lasts enough time, epimutations could facilitate assimilation into genetic changes that stabilize the new sexual system or sex-determining mechanism. Examples supporting these assertions are presented, caveats or difficulties and knowledge gaps identified, and possible ways to test this hypothesis suggested. This article is part of the theme issue ‘Challenging the paradigm in sex chromosome evolution: empirical and theoretical insights with a focus on vertebrates (Part I)’
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