Environmentally induced epigenetic changes may contribute to phenotypic plasticity, increase adaptive potential in changing environments, and play a key role in the establishment and spread of invasive species in new habitats. In this study, we used Methylation Sensitive Amplified Length Polymorphism (MS-AFLP) to assess environmentally induced DNA methylation changes in a globally invasive clonal ascidian, Didemnum vexillum. We tested the effect of increasing temperature (19, 25 and 27°C) and

more »

... creasing salinity (34, 32, 30, 28 and 26 practical salinity units (PSU) on global DNA methylation, growth and survival rates. Exposure to 27°C resulted in significant changes in DNA methylation over time, while there were no significant changes in non-methylated loci (representing genetic variation). Growth also decreased in colonies exposed to high temperatures, suggesting they were under thermal stress. In contrast, no differences in growth or DNA methylation patterns were observed in colonies exposed to a decreasing salinity gradient, potentially due to prior adaptation to conditions experienced at the site of collection. The results of this study show that environmental stress can induce significant global DNA methylation changes in an invasive marine invertebrate on very rapid timescales, and that this response varies depending on the type, magnitude, and duration of the stressor. Changes in genomic DNA methylation and the rate of growth may act to 'buy survival time' until conditions improve, and determine the distribution limits of this globally invasive species. PeerJ reviewing PDF | Manuscript to be reviewed 1 Effects of temperature and salinity stress on DNA methylation in a 2 highly invasive marine invertebrate, the colonial ascidian Didemnum 3 vexillum 4 5 6 7 8 Abstract 24 Environmentally induced epigenetic changes may contribute to phenotypic plasticity, increase 25 adaptive potential in changing environments, and play a key role in the establishment and spread 26 of invasive species in new habitats. In this study, we used Methylation-Sensitive Amplified 27 Fragment Length Polymorphism (MS-AFLP) to assess environmentally induced DNA 28 methylation changes in a globally invasive colonial ascidian, Didemnum vexillum. We tested the 29 effect of increasing temperature (19, 25 and 27°C) and decreasing salinity (34, 32, 30, 28 and 26 30 practical salinity units (PSU)) on global DNA methylation, growth and survival rates. After three 31 days of exposure to elevated temperature, significant DNA methylation differences were 32 observed between treatments. Exposure to 27°C resulted in changes in DNA methylation over 33 time, while there were no significant changes in non-methylated loci (representing genetic 34 variation). Growth also decreased in colonies exposed to high temperatures, suggesting they 35 were under thermal stress. In contrast, no differences in growth or DNA methylation patterns 36 were observed in colonies exposed to a decreasing salinity gradient, potentially due to prior 37 adaptation to conditions experienced at the site of collection. The results of this study show that 38 environmental stress can induce significant global DNA methylation changes in an invasive 39 marine invertebrate on very rapid timescales, and that this response varies depending on the type, 40 magnitude, and duration of the stressor. Changes in genomic DNA methylation and the rate of 41 growth may act to 'buy survival time' until conditions improve, and determine the distribution 42 limits of this globally invasive species. 43 44 45 PeerJ reviewing PDF |