Biological Invasions

, Volume 13, Issue 7, pp 1687–1709

Molecular markers reconstruct the invasion history of variable leaf watermilfoil (Myriophyllum heterophyllum) and distinguish it from closely related species

  • Ryan A. Thum
  • Matthew P. Zuellig
  • Robert L. Johnson
  • Michael L. Moody
  • Charles Vossbrinck
Original Paper

DOI: 10.1007/s10530-010-9927-0

Cite this article as:
Thum, R.A., Zuellig, M.P., Johnson, R.L. et al. Biol Invasions (2011) 13: 1687. doi:10.1007/s10530-010-9927-0


Genetic variation is increasingly recognized as an important factor influencing the establishment and spread of introduced species, and depends on both the introduction history and partitioning of genetic variation within and among potential source populations. We examine patterns of genetic variation in native and introduced populations of variable leaf watermilfoil, Myriophyllum heterophyllum, using chloroplast (trnL-F) and ribosomal (ITS) DNA sequences, as well as amplified fragment length polymorphisms (AFLPs). We identify a strong phylogeographic break distinguishing populations located on the Atlantic Coastal Plain (ACP) versus other (“Continental”) portions of the native range. Within these distinct biogeographic regions, we also find genetic variation to be strongly partitioned among populations as analysis of molecular variance (AMOVA) partitioned 91 and 75% of cpDNA and ITS diversity among populations, respectively. We demonstrate that the introduced ranges of variable leaf watermilfoil (northeastern and western US) result from multiple independent introductions from a variety of source populations, including lineages from both the ACP and Continental portions of the native range. In addition, we used our molecular markers to demonstrate that variable leaf watermilfoil is genetically distinct from three closely-related species that it is morphologically similar to. In particular, we demonstrate that M. heterophyllum is clearly distinct from a morphologically similar native species in the western US, M. hippuroides—whose distinctiveness from M. heterophyllum has been questioned—and therefore confirm the introduction of M. heterophyllum in the western US. Furthermore, we provide the first evidence for hybridization between these two species. Finally, our molecular markers identify previously unrecognized genetic variation in these four species, and therefore demonstrate the need for further taxonomic investigation.


Cryptic species Biotypes Hybrid vigor Clonal reproduction Hybridization 

Supplementary material

10530_2010_9927_MOESM1_ESM.doc (72 kb)
Supplementary material 1 (DOC 72 kb)
10530_2010_9927_MOESM2_ESM.doc (64 kb)
Supplementary material 2 (DOC 64 kb)
10530_2010_9927_MOESM3_ESM.doc (40 kb)
Supplementary material 3 (DOC 39 kb)
10530_2010_9927_MOESM4_ESM.doc (125 kb)
Supplementary material 4 (DOC 125 kb)

Copyright information

© Springer Science+Business Media B.V. 2010

Authors and Affiliations

  • Ryan A. Thum
    • 1
  • Matthew P. Zuellig
    • 1
  • Robert L. Johnson
    • 2
  • Michael L. Moody
    • 3
  • Charles Vossbrinck
    • 4
  1. 1.Annis Water Resources InstituteGrand Valley State UniversityMuskegonUSA
  2. 2.Ecology and Evolutionary Biology DepartmentCornell UniversityIthacaUSA
  3. 3.Department of Plant BiologyUniversity of Western AustraliaCrawleyAustralia
  4. 4.Department of Environmental ScienceConnecticut Agricultural Experiment StationNew HavenUSA

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