Assessment of hybridization between Typha spp. in North America

Abstract

<p>Typha species form a large portion of the biomass in North American marshes. Hybridization between the introduced species T. angustifolia and the native species T. latifolia has resulted in the formation of T. glauca . Studies examining the hybrid nature of T. glauca have reached different conclusions: T. glauca has been described as a separate hybrid species, a hybrid swarm, and an F1 hybrid. To discern between these hypotheses, 17 T. angustifolia -specific and 13 T. latifolia -specific markers were identified using Random Amplified Polymorphic DNA (RAPD). Specimens collected from Manitoba, Ontario, New York, Quebec and Massachusetts were examined. Each of the specimens identified as a hybrid contained all of the species-specific markers indicating an F1 hybrid status. T. angustifolia 's role as the maternal parent was supported with a species-specific chloroplast marker. Reports in the literature suggest that T. glauca may be more prevalent than the parental species at disturbed sites. To verify these reports, the species composition of a highly degraded Great Lakes marsh was examined. Since morphological variation limits accurate identification, specimens were identified using RAPD markers. Approximately 63% of the specimens were identified as T. glauca ; the hybrid dominated 4 of the 7 sites examined. Thus, changes in species composition need to be considered prior to forming revegetation plans. Since molecular analysis may not always be feasible, morphological characters were examined for genetically-identified specimens. Discriminant analysis of leaf width, spike length, spike interval and stigma width provided quantitative identification of the three taxa, although identification was more accurate for T. latifolia (95%) and T. angustifolia (93%) than for T. glauca (83%). These characters can be used to examine the ecological role of T. glauca ; however, molecular markers are still necessary for the identification of seedlings, rootstocks, and plants without flowering spikes, as well as for the classification of hybrids.</p>