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Premise : Studies of hybridizing species are facilitated by the availability of species-specifi c molecular markers for identifying early- and later-generation hybrids. Cattails are a dominant feature of wetland communities, and a better understanding of the prevalence of hybrids is needed to assess the ecological and evolutionary effects of hybridization. Hybridization between Typha angustifolia and T. latifolia produce long-lived clones, known as Typha × glauca , which are considered to be invasive. Although morphological variation in cattails makes it diffi cult to recognize early- and later-generation hybrids, several dominant, species-specifi c RAPD markers are available. Our goal was to fi codominant, species-specifi c markers with greater polymorphism than RAPDs, to identify later-generation hybrids more effi ciently. Methods : We screened nine SSR (simple sequence repeat) loci that were described from populations in Ukraine, and we surveyed 31 cattail populations from the upper Midwest and eastern USA. Key results : Seven SSR loci distinguished the parent taxa and were consistent with known species-specifi c RAPD markers, allowing easier detection of backcrossing. We used linear discriminant analysis to show that F 1 hybrid phenotypes were intermediate between the parent taxa, while those of backcrossed plants overlapped with the hybrids and their parents. Log(leaf length/leaf width), spike gap length, spike length, and stem diameter explained much of the variation among groups. Conclusions : We provide the fi rst documentation of backcrossed plants in hybridizing cattail populations in Michigan. The diagnostic SSR loci we identifi ed should be extremely useful for examining the evolutionary and ecology interactions of hybridizing cattails in North America. |
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