ARS | Publication request: Introgression between saltcedars (Tamarix chinensis and T. ramosissima) in the USA invasion

Submitted to: Biological Invasions
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: October 24, 2007
Publication Date: November 4, 2008
Repository URL: http://hdl.handle.net/10113/28656
Citation: Gaskin, J.F., Kazmer, D.J. 2008. Introgression between saltcedars (Tamarix chinensis and T. ramosissima) in the USA invasion. Biological Invasions. 11(5):1121-1130.

Interpretive Summary: Saltcedars (Tamarix ramosissima and T. chinensis) are native to Asia, but since introduction into the USDA, have become common and invasive in many western riparian habitats. In their native range, the two species do not seem to interbreed, but in the USA we found over 80% of the plants were hybrids of the two species. The high percentage of novel hybrids may have implications for classical biological control efforts.

Technical Abstract: Saltcedars (Tamarix ramosissima and T. chinensis) are native to Asia, but since introduction into the USDA, 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 invasion many of the plants (23%) are novel hybrids. Here, we used a multilocus DNA marker (AFLPs) to determine the level of introgression in USA plants. Diagnostic bands, principal coordinate analysis, and a Bayesian approach (NewHybrids) all indicated a much higher incidence of hybridization (84-87%) than was revealed by the single locus marker, with USA plants forming a genotypic continuum between the two parental types. Concordance of level of introgression was highest between principal coordinate analysis and the Bayesian analysis. The high percentage of novel hybrids may have implications for classical biological control efforts.