Biological Invasions

, Volume 11, Issue 5, pp 1121–1130 | Cite as

Introgression between invasive saltcedars (Tamarix chinensis and T. ramosissima) in the USA

  • John F. Gaskin
  • David J. Kazmer
Original Paper


Saltcedars (Tamarix ramosissima and T. chinensis) are native to Asia, but since introduction into the USA have become common and invasive in many western riparian habitats. Recent molecular analysis of a single locus nuclear DNA sequence marker has shown that in their native range the two species are genetically distinct, but within the USA populations many of the plants (23%) are novel hybrids. Here, we used multilocus DNA markers (amplified fragment length polymorphisms) to determine the levels of introgression in USA plants. Species-specific diagnostic markers, principal coordinates analysis, and a Bayesian model-based clustering analysis all indicate a much higher incidence of hybridization (83–87%) than was revealed by the single locus marker, with USA plants forming a genetic continuum between the two parental types. Additionally, the level of introgression toward Tamarix ramosissima or T. chinensis was strongly correlated with latitude. Concordance of level of introgression was highest between principal coordinates analysis and the Bayesian analysis. The high percentage of novel hybrids may have implications for classical biological control efforts.


AFLP Introgression Hybridization Invasion Saltcedar Tamarix 



Amplified fragment length polymorphism


Principal coordinate analysis


Unweighted pair group matching algorithm


Phosphoenolpyruvate carboxylase



We thank D. Branson and three anonymous reviewers for helpful comments on this manuscript, Adam Birken, David Cooper, George Yatskievych, and others for donating plant samples, and Kim Mann and Jeannie Lassey for AFLP and DNA sequencing in the laboratory. This research was made possible through funding from the National Geographic Society Committee for Research and Exploration Grant # 6663-99, the Bureau of Land Management (Montana, South and North Dakota), the Bureau of Indian Affairs (Rocky Mountain Office), and U.S. Department of Agriculture National Research Initiative Competitive Grants Program, Cooperative State Research, Education, and Extension Service Grant 2000-00836.


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Copyright information

© U.S. Government 2008

Authors and Affiliations

  1. 1.Northern Plains Agricultural Research LaboratoryUSDA-ARSSidneyUSA

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