The epigenetic footprint of poleward range‐expanding plants in apomictic dandelions

Abstract

Epigenetic modifications, such as DNA methylation variation, can generate heritable phenotypic variation independent of the underlying genetic code. However, epigenetic variation in natural plant populations is poorly documented and little understood. Here, we test whether northward range expansion of obligate apomicts of the common dandelion (Taraxacum officinale) is associated with DNA methylation variation. We characterized and compared patterns of genetic and DNA methylation variation in greenhouse-reared offspring of T. officinale that were collected along a latitudinal transect of northward range expansion in Europe. Genetic AFLP and epigenetic MS-AFLP markers revealed high levels of local diversity and modest but significant heritable differentiation between sampling locations and between the southern, central and northern regions of the transect. Patterns of genetic and epigenetic variation were significantly correlated, reflecting the genetic control over epigenetic variation and/or the accumulation of lineage-specific spontaneous epimutations, which may be selectively neutral. In addition, we identified a small component of DNA methylation differentiation along the transect that is independent of genetic variation. This epigenetic differentiation might reflect environment-specific induction or, in case the DNA methylation variation affects relevant traits and fitness, selection of heritable DNA methylation variants. Such generated epigenetic variants might contribute to the adaptive capacity of individual asexual lineages under changing environments. Our results highlight the potential of heritable DNA methylation variation to contribute to population differentiation along ecological gradients. Further studies are needed using higher resolution methods to understand the functional significance of such natural occurring epigenetic differentiation.

Epigenetics in natural animal populations

“…Herrera & Bazaga, 2010), and principal coordinate analyses (PCoA) can be equally useful in describing population differentiation at the epigenetic level (e.g. Gao et al, 2010;Wenzel & Piertney, 2014;Preite et al, 2015). Correlations between population statistics for genetic vs. epigenetic variation can potentially be analysed using a Mantel test (e.g.…”

Epigenetic Inheritance across the Landscape

“…Both genome-wide genetic and epigenetic variation in Arabidopsis were correlated with climate and spatial variables across Sweden and Eurasia (Keller et al, 2016). However, such correlations are not always found, as was the case for in dandelion ( Taraxacum officinale ) across a north–south transect from Luxembourg to central Sweden, where no gradient in DNA methylation was found (Preite et al, 2015). Correlations between epigenetic variation and the environment may be inconsistent between species in the same environments.…”

“…A number of very recent landscape-level studies have investigated the role of epigenetics in intra-specific trait variation and adaptation (Medrano et al, 2014; Dubin et al, 2015; Preite et al, 2015; Foust et al, 2016; Gugger et al, 2016; Herrera et al, 2016; Keller et al, 2016). These studies focus on at least one of the following: (i) the relationship between genetic and epigenetic variation at the landscape level, (ii) correlations between environmental variables and epigenetic status, and (iii) correlations between epigenetic status and plant functional traits.…”

“…These scenarios might include: rapidly changing environments, such as those predicted by climate change models; species with low genetic variation due to asexual reproduction or founder effects; and organisms with long generation times (Bossdorf et al, 2008; Bonduriansky and Day, 2009; Nicotra et al, 2010; Castonguay and Angers, 2012). Despite potentially greater importance in the evolution of long-lived and asexual species, most empirical work so far has been done in sexually reproducing annuals (but see Richards et al, 2012; Zas et al, 2013; Yakovlev et al, 2014; Preite et al, 2015). Thus, not only may epigenetic-based transgenerational inheritance be a source of adaptive variation across a variety of species, it may be particularly important to organisms such as clonal grasses and long-lived trees, many of which are ecologically important foundation species.…”

Genetic and epigenetic changes during the invasion of a cosmopolitan species (Phragmites australis)

“…Epigenetic diversity can generate massive heritable variation of ecologically relevant plant traits such as root allocation, drought tolerance and nutrient plasticity (Zhang, Fischer, Colot, & Bossdorf, 2013), and it appears to increase the productivity and stability of plant populations in Arabidopsis thaliana under artificial conditions (Latzel et al., 2013). An increasing number of studies have also demonstrated the common existence and significant role of epigenetic variation in plant populations of herbs (Foust et al., 2016; Herrera, Medrano, & Bazaga, 2014; Medrano et al., 2014; Preite et al., 2015; Schulz, Eckstein, & Durka, 2014), shrubs (Avramidou, Ganopoulos, Doulis, Tsaftaris, & Aravanopoulos, 2015; Herrera & Bazaga, 2013, 2016), and trees (Guarino, Cicatelli, Brundu, Heinze, & Castiglione, 2015; Gugger, Fitz‐Gibbon, PellEgrini, & Sork, 2016; Lira‐Medeiros et al., 2010; Platt, Gugger, Pellegrini, & Sork, 2015; Sáez‐Laguna et al., 2014) under natural conditions. Therefore, epigenetic variation can be a very important mechanism for invasive plant success in a broad range of environments (Douhovnikoff & Dodd, 2014; Richards, Schrey, & Pigliucci, 2012).…”