PS 87-141 - A population genetic approach to understanding the influence of land use on the distribution of Ambrosia artemisiifolia in New England

Friday, August 12, 2011
Exhibit Hall 3, Austin Convention Center
Sara D. Niedbalski1, Jason S. McLachlan2, Candice Y. Lumibao1, Kelsey Flood1 and Dan Williams3, (1)Biological Sciences, University of Notre Dame, Notre Dame, IN, (2)Department of Biology, University of Notre Dame, Notre Dame, IN, (3)Biological Sciences, University of Notre Dame, Notre Dame

Common Ragweed, Ambrosia artemisiifolia, is the leading cause of Allergenic Airway Disease in North America, and therefore an understanding of this species’ distribution patterns is of chief importance to health officials and individuals susceptible to the often-deadly effects of this plant. Previous research has shown that ecotypic variation in ragweed due to climate factors correlates to allergenicity, but it remains unclear as to whether anthropogenic forces, such as land use, might also affect the distribution of this species. Population genetics offers a useful way to infer the causes of population expansion and spread across varying landscapes when coupled with thorough field observations and sampling. A diverse combination of land-use in the state of Massachusetts makes it an ideal location to study the effects of land use on the genetic structure of ragweed. Using five microsatellite markers, 30 populations of ragweed from across the state were genotyped. Preliminary analyses focus on three distinct geographical areas of Massachusetts, which also vary in land use: rural, forested sites in the Berkshire Mountains, suburban locations in the Connecticut River valley, and densely urbanized populations in central Massachusetts. This study examines the genetic variation among and between sites across this gradient. 


Preliminary analyses found the mean expected heterozygosity (He) across all populations and all loci to be 0.6158. The rural mountain populations were found to have a lower mean expected heterozygosity (He = 0.46) than those populations occurring in the more urbanized sites of the Connecticut River valley and central Massachusetts (He = 0.7), however this was not found to be significant (p=0.10513). Additionally, a cluster analysis performed in BAPS showed each of the 6 populations included in this preliminary analysis to be significantly different from each other. Continued analysis will give a more accurate picture of just how the genetic structure of these populations are correlated to land use, which will ultimately allow us to draw conclusions based on the factors contributing to the spread of ragweed populations throughout the state. Understanding the population structure of this allergenic species, as well as the driving factors of it’s distribution, will be important to health officers, land managers, and city officials concerned with minimizing the detrimental effects of this weed, including allergenic airway disease, asthma, and seasonal allergies.

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