Reassessment of Molecular Variation in Isolated Populations of Deschampsia cespitosa from Metal Contaminated Regions in Northern Ontario (Canada) after 17 Years of Potential Genetic Recombination

The effects of ore extraction and processing procedures in the Greater Sudbury and Cobalt regions have been long-lasting. The objective of this study is to determine the current level of genetic variation in Deschampsia cespitosa populations from metal contaminated and uncontaminated sites in samples collected in Northern Ontario in 2016 after 17 years of potential genetic recombination since the last study in 1999. D. cespitosa leaf samples collected from the City of Greater Sudbury (CGS), Cobalt and Little Current were analyzed using ISSR primers. The levels of genetic variation were moderate to high within targeted populations. There was no significant difference (p≤0.05) in the overall percent of polymorphic loci in metal-uncontaminated site of Little Current (from 70% in 1999 to 77% in 2016) and in a Cobalt Cart Lake site (from 48% in 1999 to 55% in 2016). But a significant decrease in genetic variation was observed in CGS Wahnapitae site (from 72% in 1999 to 54% in 2016). On the other hand, a significant increase was observed in Cobalt Nipissing (from 46% in 1999 to 64% in 2016). The Kelly Lake site in the CGS with the lowest level of polymorphic loci (42.5%) in 2016 was not surveyed in 1999. The degree of genetic relatedness among sites has increased since the populations are more genetically closely related than 17 years ago. No population-specific ISSR marker was identified. The clustering of Cobalt and Sudbury populations strengthens the earlier theory that Sudbury populations of D. cespitosa might be from the Cobalt region.