Ecological Epigenetics

Cuiping

et al. 2018

Ecology and Evolution

While many introduced invasive species can increase genetic diversity through multiple introductions and/or hybridization to colonize successfully in new environments, others with low genetic diversity have to persist by alternative mechanisms such as epigenetic variation. Given that Phragmites australis is a cosmopolitan reed growing in a wide range of habitats and its invasion history, especially in North America, has been relatively well studied, it provides an ideal system for studying the role and relationship of genetic and epigenetic variation in biological invasions. We used amplified fragment length polymorphism (AFLP) and methylation‐sensitive (MS) AFLP methods to evaluate genetic and epigenetic diversity and structure in groups of the common reed across its range in the world. Evidence from analysis of molecular variance (AMOVA) based on AFLP and MS‐AFLP data supported the previous conclusion that the invasive introduced populations of P. australis in North America were from European and Mediterranean regions. In the Gulf Coast region, the introduced group harbored a high level of genetic variation relative to originating group from its native location, and it showed epigenetic diversity equal to that of the native group, if not higher, while the introduced group held lower genetic diversity than the native. In the Great Lakes region, the native group displayed very low genetic and epigenetic variation, and the introduced one showed slightly lower genetic and epigenetic diversity than the original one. Unexpectedly, AMOVA and principal component analysis did not demonstrate any epigenetic convergence between native and introduced groups before genetic convergence. Our results suggested that intertwined changes in genetic and epigenetic variation were involved in the invasion success in North America. Although our study did not provide strong evidence proving the importance of epigenetic variation prior to genetic, it implied the similar role of stable epigenetic diversity to genetic diversity in the adaptation of P. australis to local environment.

Section: Discussionmentioning

confidence: 99%

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

Cuiping

et al. 2018

Ecology and Evolution

“…Populations of asexual hybrids may also be able to deal with rapid environmental change through phenotypic plasticity (Nicotra et al ., ). Additionally, epigenetic variation can also contribute to rapid adaptation to environmental challenges, as suggested by the ecologically differentiated populations of the invasive species Fallopia japonica which display abundant epigenetic diversity, despite genetic uniformity (Kilvitis et al ., ). The variety of mechanisms available to asexual hybrid populations to adapt to different environments may make hybrids more resilient to the rapid modifications brought by global change.…”

Section: Hybrid Establishment: Overcoming Intrinsic and Extrinsic Posmentioning

confidence: 97%

Hybridization and hybrid speciation under global change

2016

Contents Summary1170I.Introduction1170II.Hybrid formation1172III.Hybrid establishment: overcoming intrinsic and extrinsic post‐zygotic barriers1175IV.Outcomes of hybridization1180V.Outlook1183Acknowledgements1184References1184 Summary An unintended consequence of global change is an increase in opportunities for hybridization among previously isolated lineages. Here we illustrate how global change can facilitate the breakdown of reproductive barriers and the formation of hybrids, drawing on the flora of the British Isles for insight. Although global change may ameliorate some of the barriers preventing hybrid establishment, for example by providing new ecological niches for hybrids, it will have limited effects on environment‐independent post‐zygotic barriers. For example, genic incompatibilities and differences in chromosome numbers and structure within hybrid genomes are unlikely to be affected by global change. We thus speculate that global change will have a larger effect on eroding pre‐zygotic barriers (eco‐geographical isolation and phenology) than post‐zygotic barriers, shifting the relative importance of these two classes of reproductive barriers from what is usually seen in naturally produced hybrids where pre‐zygotic barriers are the largest contributors to reproductive isolation. Although the long‐term fate of neo‐hybrids is still to be determined, the massive impact of global change on the dynamics and distribution of biodiversity generates an unprecedented opportunity to study large numbers of unpredicted, and often replicated, hybridization ‘experiments’, allowing us to peer into the birth and death of evolutionary lineages.

“…The potential contributions of epigenetics to plant adaptation and evolution have been thoroughly outlined, but their impact on natural populations remains understudied (e.g. Grant‐Downton & Dickinson, ; Jablonka & Raz, ; Hirsch et al ., ; Kilvitis et al ., ). Polyploidization, that is, the possession of at least three complete sets of chromosomes, has long been recognized as a major evolutionary force in plants.…”

Section: Introductionmentioning

confidence: 99%

Epigenetic contribution to successful polyploidizations: variation in global cytosine methylation along an extensive ploidy series in Dianthus broteri (Caryophyllaceae)

et al. 2016

Polyploidization is a significant evolutionary force in plants which involves major genomic and genetic changes, frequently regulated by epigenetic factors. We explored whether natural polyploidization in Dianthus broteri complex resulted in substantial changes in global DNA cytosine methylation associated to ploidy. Global cytosine methylation was estimated by high-performance liquid chromatography (HPLC) in 12 monocytotypic populations with different ploidies (2×, 4×, 6×, 12×) broadly distributed within D. broteri distribution range. The effects of ploidy level and local variation on methylation were assessed by generalized linear mixed models (GLMMs). Dianthus broteri exhibited a higher methylation percent (˜33%) than expected by its monoploid genome size and a large variation among study populations (range: 29.3-35.3%). Global methylation tended to increase with ploidy but did not significantly differ across levels due to increased variation within the highest-order polyploidy categories. Methylation varied more among hexaploid and dodecaploid populations, despite such cytotypes showing more restricted geographic location and increased genetic relatedness than diploids and tetraploids. In this study, we demonstrate the usefulness of an HPLC method in providing precise and genome reference-free global measure of DNA cytosine methylation, suitable to advance current knowledge of the roles of this epigenetic mechanism in polyploidization processes.