PARENT SESSION
Poster Session 20: Invasive Species
Wednesday, August 10, 5:00 PM - 6:30 PM, Exhibit Hall 220 A-E, Level 2, Palais des congrès de Montréal

Ecological genetics of a milfoil invasion.

Thum, Ryan^{*,1, 2}, Lennon, Jay^{1, 3}, ¹ Dartmouth College, Hanover, NH, USA² Cornell University, Ithaca, NY, USA³ Brown University, Providence, RI, USA

ABSTRACT- Variable leaf water milfoil, Myriophyllum heterophyllum, has rapidly spread throughout portions of New England and is associated with decreased native macrophyte diversity and property values and interferes with lake recreational activity. Although its spread has been blamed on human-mediated dispersal vectors, the causes of invasive growth after colonization in lakes are unknown. Two hypotheses for invasive growth contrast in their emphasis on the roles of genetic versus environmental factors. Heterosis, or hybrid vigor, has been suggested as a mechanism for invasive growth. Alternatively, dispersal limitation and or human alteration to lake habitats emphasize environmental factors. We surveyed New Hampshire lakes for the presence of hybrid genotypes, which are expected if heterosis contributes to invasive growth. However, we found no hybrid genotypes in New Hampshire lakes, suggesting that environmental factors, rather than genetic, are more important for invasive growth in this area. We are currently exploring the role of environmental factors through spatial statistical techniques on a large dataset of environmental variables for New Hampshire lakes.

Key words: invasive species, macrophyte