Epigenetics and the success of invasive plants

Abstract

Biological invasions impose ecological and economic problems on a global scale, but also provide extraordinary opportunities for studying contemporary evolution. It is critical to understand the evolutionary processes that underly invasion success in order to successfully manage existing invaders, and to prevent future invasions. As successful invasive species sometimes are suspected to rapidly adjust to their new environments in spite of very low genetic diversity, we are obliged to re-evaluate genomic-level processes that translate into phenotypic diversity. In this paper, we review work that supports the idea that trait variation, within and among invasive populations, can be created through epigenetic or other non-genetic processes, particularly in clonal invaders where somatic changes can persist indefinitely. We consider several processes that have been implicated as adaptive in invasion success, focusing on various forms of 'genomic shock' resulting from exposure to environmental stress, hybridization and whole-genome duplication (polyploidy), and leading to various patterns of gene expression re-programming and epigenetic changes that contribute to phenotypic variation or even novelty. These mechanisms can contribute to transgressive phenotypes, including hybrid vigour and novel traits, and may thus help to understand the huge successes of some plant invaders, especially those that are genetically impoverished. This article is part of the theme issue 'How does epigenetics influence the course of evolution?'

Keywords: biological invasion; clonal reproduction; hybridization; metabolomics; polyploidy; rapid evolution.

Figure 1.

Hypothetical relationships between genetic, epigenetic and phenotypic variation in invasive compared to native populations. Three segments of the genome are shown for each of three individuals from native (top panel) and invasive (lower panel) populations. The horizontal bars are the DNA, with differences in DNA sequence indicated by different colours. Epigenetic modifications at a particular DNA fragment are indicated by the black triangles. Natural epigenetic variation may be found within or between ranges. Epigenetic variation can be independent of or confounded with genetic variation. Some epigenetic variation in natural populations may be plastic and not heritable, i.e. it will not persist in a common environment. If independent epigenetic variation persists in a common environment, this is evidence for epigenetic inheritance. If this heritable epigenetic variation translates into phenotypic and fitness differences (as illustrated above), it could contribute to invasion success. Modified from Bossdorf et al. [86]. (Online version in colour.)