Degree Name
MS (Master of Science)
Program
Biology
Date of Award
12-2007
Committee Chair or Co-Chairs
Foster Levy
Committee Members
Dhirena Kumar, Timothy D. McDowell
Abstract
Phacelia purshii Buckley and P. fimbriata Micheaux are two species that are nearly morphologically indistinguishable. Seed germination experiments showed that the high elevation endemic, P. fimbriata requires lower temperatures to trigger germination. Following interspecific crosses, pollen tubes enter ovules and maternal tissue of the gynoecium matures but hybrid diploid and triploid organs fail to develop. DNA sequences from the ribosomal DNA internal transcribed region showed that P. fimbriata and P. purshii comprise a monophyletic clade but that P. fimbriata is more differentiated from related species. In contrast, P. purshii supported significantly higher levels of intraspecific polymorphism. Phacelia fimbriata and P. purshii are sister species with similar morphology but they are unable to hybridize, they are differentiated in physiological characteristics related to environment, and they inhabit different elevations. This pattern of relationship and differentiation suggests P. fimbriata may be the product of ecological speciation.
Document Type
Thesis - unrestricted
Recommended Citation
Glass, Pamela Michele, "Evidence of Ecological Speciation in Phacelia." (2007). Electronic Theses and Dissertations. Paper 2143. https://dc.etsu.edu/etd/2143
Copyright
Copyright by the authors.