Although interspecific hybridization in plants often results in sterility, occasionally hybrids show evidence of fertility. Because of their reproductive competence, such F1's have the ability to interbreed with each other and with their parents, forming introgressive offspring that are morphologically intermediate between the original parental forms. North American Diphasiastrum complanatum, D. digitatum, and D. tristachyum exhibit evidence of such introgressive hybridization. To test for introgression, morphological measurements for parental and putative hybrid taxa were collected and analyzed using principle components analyses and hybrid indices. Spore fertility was also analyzed within the study set. Results support the presence of introgression among all three pair combinations. Although not infrequent, the numbers of hybrid forms are far exceeded by parental forms and so there are no compelling reasons not to recognize these three taxa at the species level.
|Advisor:||Hickey, R. James|
|Commitee:||Moore, Richard C., Vincent, Michael A.|
|School Location:||United States -- Ohio|
|Source:||MAI 56/05M(E), Masters Abstracts International|
|Subjects:||Biology, Plant biology|
|Keywords:||Diphasiastrum, Hybridization, Introgression, Lycopodiaceae, Lycopodium, Morphology|
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