Hybridization, cryptic diversity, and invasiveness in introduced variable-leaf watermilfoil
Article first published online: 10 MAY 2012
© 2012 The Authors. Evolutionary Applications published by Blackwell Publishing Ltd.
This is an open access article under the terms of the Creative Commons Attribution-NonCommercial License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited and is not used for commercial purposes.
Volume 5, Issue 8, pages 892–900, December 2012
How to Cite
Tavalire, H. F., Bugbee, G. E., LaRue, E. A. and Thum, R. A. (2012), Hybridization, cryptic diversity, and invasiveness in introduced variable-leaf watermilfoil. Evolutionary Applications, 5: 892–900. doi: 10.1111/j.1752-4571.2012.00267.x
- Issue published online: 24 DEC 2012
- Article first published online: 10 MAY 2012
- Manuscript Accepted: 8 APR 2012
- Manuscript Received: 22 NOV 2011
- Michigan Space Grant Consortium
- Northeast Aquatic Plant Management Society
- Midwest Aquatic Plant Management Society
- Grand Valley State University Presidential Research
- National Science Foundation. Grant Numbers: DEB-0918553, DBI-0922591
- amplified fragment length polymorphisms;
- cryptic invasion;
Hybridization may be important in the evolution of invasiveness, but few empirical studies compare introduced hybrid and parental lineages. Invasive ‘variable-leaf watermilfoil’ (Myriophyllum heterophyllum) in the northeastern United States consists of at least three distinct lineages: an interspecific hybrid (M. heterophyllum × Myriophyllum laxum) and two historically allopatric lineages of pure M. heterophyllum. Previous observations suggested that hybrid populations of variable-leaf watermilfoil may be comparatively more ‘invasive’ than pure lineages. However, no quantitative data comparing hybrid and parental lineages have been collected, nor has invasiveness been compared between parental lineages. Here, we demonstrate that these distinct lineages are also ecologically distinct. We find some support for the hypothesis that hybridization has played a role in the evolution of invasiveness: hybrids exhibited higher biomass, individual plant size, and greater branching than at least one parental lineage of M. heterophyllum. However, parental lineages did not differ from the hybrid for some traits, demonstrating that pure parental lineages can also be invasive. In addition, we found no evidence for a role of intraspecific hybridization in the evolution of invasiveness in these lineages of variable-leaf watermilfoil, even where they co-occurred locally. Our study suggests that distinguishing among cryptic lineages will help prioritize rapid response control efforts.