Genetic and epigenetic variation in Spartina alterniflora following the Deepwater Horizon oil spill

Abstract

Catastrophic events offer unique opportunities to study rapid population response to stress in natural settings. In concert with genetic variation, epigenetic mechanisms may allow populations to persist through severe environmental challenges. In 2010, the Deepwater Horizon oil spill devastated large portions of the coastline along the Gulf of Mexico. However, the foundational salt marsh grass, Spartina alterniflora, showed high resilience to this strong environmental disturbance. Following the spill, we simultaneously examined the genetic and epigenetic structure of recovering populations of S. alterniflora to oil exposure. We quantified genetic and DNA methylation variation using amplified fragment length polymorphism and methylation sensitive fragment length polymorphism (MS‐AFLP) to test the hypothesis that response to oil exposure in S. alterniflora resulted in genetically and epigenetically based population differentiation. We found high genetic and epigenetic variation within and among sites and found significant genetic differentiation between contaminated and uncontaminated sites, which may reflect nonrandom mortality in response to oil exposure. Additionally, despite a lack of genomewide patterns in DNA methylation between contaminated and uncontaminated sites, we found five MS‐AFLP loci (12% of polymorphic MS‐AFLP loci) that were correlated with oil exposure. Overall, our findings support genetically based differentiation correlated with exposure to the oil spill in this system, but also suggest a potential role for epigenetic mechanisms in population differentiation.

Genetic and epigenetic variations associated with adaptation to heterogeneous habitat conditions in a deciduous shrub

“…Consistent with previous studies of other species distributed across different habitats observing equal or higher epigenetic than genetic diversity (Foust et al, 2016;Herrera & Bazaga, 2010;Richards, Schrey, & Pigliucci, 2012;Schulz, Eckstein, & Durka, 2014), we found slightly higher levels of epigenetic than genetic diversity in V. negundo and epigenetic variation and habitat may show different patterns in varying species. When running simple and partial Mantel tests, we obtained the same pattern as for Borrichia frutescens (Foust et al, 2016), failing to detect any relationship between epigenetic and habitat environment using crude binary data to describe complex habitats, as we had a larger number and range of sampling plots than the previous studies (Foust et al, 2016;Kim et al, 2016;Robertson, Schrey, Shayter, Moss, & Richards, 2017;Schulz et al, 2014). Limited studies have been conducted of epigenetic differentiation in natural populations across heterogeneous habitat conditions, and there is an urgent need to develop or replace the binary method to comprehensively characterize the complex habitat conditions.…”

“…The epigenetic mechanism may be restricted when natural plant populations endure some discrete human‐caused disturbance, such as heavy metal pollution (Kim et al., ), experimental disturbance (Herrera & Bazaga, ), and oil spills (Robertson et al., ). According to our field investigations and planting experiments (Du et al., ), Chinese chastetree tends to distribute in open habitats with plentiful light.…”

“…The epigenetic mechanism may be restricted when natural plant populations endure some discrete human-caused disturbance, such as heavy metal pollution (Kim et al, 2016), experimental disturbance , and oil spills (Robertson et al, 2017).…”

Methylation divergence of invasive Ciona ascidians: Significant population structure and local environmental influence

“…However, the proportion of environmental‐related subepiloci in our study was much less than that in red grouse Lagopus lagopus scotica associated with gastrointestinal parasite load (13.6%; Wenzel & Piertney, ). Likewise, 12% of polymorphic epiloci in Spartina alterniflora were found to be correlated with oil exposure (Robertson, Schrey, Shayter, Moss, & Richards, ). The different ratios among studies may result from the difference of stresses and degree of stresses.…”

Transcriptome response of the foundation plant Spartina alterniflora to the Deepwater Horizon oil spill

“…Spartina alterniflora also shows remarkable resilience to a variety of stressors (Baisakh & Subudhi, 2009;Baisakh, Subudhi, & Varadwaj, 2008;Pennings & Bertness, 2001;Silliman et al, 2012). Oil-affected populations showed up to 100% recovery within seven months of the DWH spill, despite the immediate effects of reduced carbon fixation and transpiration (Lin & Mendelssohn, 2012;Lin et al, 2016;RamanaRao, Weindorf, Breitenbeck, & Baisakh, 2012;Silliman et al, 2012), and evidence for genetic divergence of oil-exposed populations from nearby uncontaminated populations (Robertson, Schrey, Shayter, Moss, & Richards, 2017). Prior studies in S. alterniflora under controlled conditions have examined expression of candidate genes in response to heat, salt or oil stressors (Baisakh & Subudhi, 2009;Baisakh et al, 2008;RamanaRao et al, 2012), and Bedre, Mangu, Srivastava, Sanchez, and Baisakh (2016) recently characterized the full transcriptome response to salinity.…”