Conference Name: Northeast Aquatic Plant Management Society (NEAPMS) 2011
In recent years, it has been suggested that aquatic invasive species may harbor ecologically distinct biotypes, and that such biotypes may have different impacts, potential for spread, or response to management. Yet, very few studies have been done to compare the ecologies of distinct biotypes. Genetic studies of Myriophyllum heterophyllum (variable-leaf watermilfoil, VLM) - an invasive aquatic plant throughout New England - have identified distinct genetic lineages that have independently invaded the northeastern US from different geographic origins. However, it is not known whether these distinct lineages differ in their ecology, an area where knowledge could greatly impact the design of management regimes. We compared the growth habits of the three most common introduced genotypes of VLM in New England. We compared plant size, several morphological measures, bed densities, and bed area in an observational study across 21 lakes. We also grew the three genotypes in a common garden under a variety of environmental conditions to assess the genetic basis of differences in growth forms. Ongoing analyses suggest significant differences in growth form and pattern across both studies. This study therefore demonstrates the utility of using genetic screens to identify and compare the ecology and management of distinct biotypes. For example, the ecological differences revealed in this study can be incorporated into models for the spread and impact of different biotypes. In addition, our study suggests that studies of management efficacy should explicitly incorporate the diversity of introduced genotypes, as ecologically distinct biotypes are likely to differ in their levels of tolerance for different management regimes.