Date of Award

12-1998

Degree Type

Thesis

Degree Name

Doctor of Philosophy (PhD)

Department

Biology

Supervisor

Dr. Bradley N. White

Abstract

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.


Download

Included in

Biology Commons

Share

COinS