Theses and Dissertations at Montana State University (MSU)
Permanent URI for this communityhttps://scholarworks.montana.edu/handle/1/732
Browse
2 results
Search Results
Item Hybridization and invasiveness in Eurasian watermilfoil (Myriophyllum spicatum): is prioritizing hybrids in management justified?(Montana State University - Bozeman, College of Agriculture, 2021) Hoff, Hannah Katherine; Chairperson, Graduate Committee: Ryan Thum; Ryan A. Thum was a co-author of the article, 'Hybridization and invasiveness in Eurasian watermilfoil (Myriophyllum spicatum): is prioritizing hybrids in management justified?' submitted to the journal 'Invasive plant science and management' which is contained within this thesis.Hybridization can play an important role in the evolution of invasiveness. Eurasian watermilfoil (Myriophyllum spicatum L.) is a widespread aquatic invasive plant species that hybridizes with native northern watermilfoil (Myriophyllum sibiricum Kom.). Previous studies have found mixed evidence for whether hybrid watermilfoil (Myriophyllum spicatum x sibiricum) and pure M. spicatum differ in vegetative growth rate and herbicide response. While several studies have emphasized variation in these traits among M. spicatum x sibiricum genotypes, variation within M. spicatum has not been considered. Therefore, it is unclear how important genetic variation within M. spicatum, versus between M. spicatum and M. spicatum x sibiricum, is in influencing invasive traits and management outcomes. If M. spicatum x sibiricum genotypes are always more invasive than M. spicatum genotypes, simply distinguishing taxa may be sufficient for identifying lake management priorities; however, if significant phenotypic overlap is observed between taxa, distinguishing individual genotypes may be important for tailoring management strategies. We performed replicated trials of a vegetative growth and 2,4-D assay to measure clonal variation in growth rate and herbicide response of M. spicatum and M. spicatum x sibiricum. Our results indicate that M. spicatum x sibiricum exhibits higher average vegetative growth than M. spicatum, whether or not it is treated with 2,4-D. We did not observe interactions between taxon and treatment or between genotype and treatment. Despite differences between M. spicatum and M. spicatum x sibiricum in average vegetative growth, there was substantial overlap between taxa. For example, we found that the fastest-growing genotype of pure M. spicatum did not differ significantly in average growth from the fastest-growing M. spicatum x sibiricum genotype. The potential for overlap between these invasive Myriophyllum taxa suggests that distinguishing and characterizing genotypes may be more informative for management than simply distinguishing between M. spicatum and M. spicatum x sibiricum.Item Integrating DNA fingerprinting of invasive watermilfoil strains into aquatic vegetation monitoring and assessment(Montana State University - Bozeman, College of Agriculture, 2021) Gannon, Kathryn Alta; Chairperson, Graduate Committee: Ryan Thum; Raymond Newman and Ryan Thum were co-authors of the article, 'Integrating DNA fingerprinting of invasive watermilfoil strains into aquatic vegetation monitoring and assessment' submitted to the journal 'Journal of aquatic plant management' which is contained within this thesis.Eurasian watermilfoil (Myriophyllum spicatum L.) and its hybrids with native northern watermilfoil (Myriophyllum spicatum L. x Myriophyllum sibiricum) (invasive watermilfoils) are among the most heavily managed invasive aquatic plants in the United States. Within invasive watermilfoils there are distinct strains which are produced through sexual reproduction and can be maintained indefinitely by clonal propagation. Different strains can differ in their invasiveness (e.g., growth and potential for spread) and response to herbicides. However, strain identification is not routinely implemented as part of management planning or evaluation. In this thesis, we integrated molecular fingerprinting that can distinguish different Eurasian and hybrid watermilfoil strains into aquatic vegetation monitoring in eight Minnesota lakes over the course of three years. We provide proof of concept that by tracking strain incidence over time it is possible 1) to detect changes in strain composition of invasive watermilfoil populations, and 2) to identify priority strains for future growth and herbicide assays. This study demonstrates that integrating genetic fingerprinting into aquatic vegetation management and evaluation holds promise to inform management decisions by identifying those strains that have the most invasive potential. As far as we are aware, this is the first published study to examine the strain composition of invasive watermilfoil populations over time.