Abstract Detail



Systematics

Rogers, Lauren [1], Vincent, Michael [2].

Revision of the Trifolium gracilentum species complex.

The clover genus, Trifolium (Fabaceae-Papilionoideae), is extremely diverse and economically important. However, many of the taxonomic relationships within the genus, especially among the North American species, are still uncertain. One grade of clover species with unresolved relationships is the T. gracilentum species complex, which is native to the western coast of North America. The T. gracilentum species complex currently includes 6 taxa (T. bifidum var. bifidum, T. bifidum var. decipiens, T. ciliolatum, T. gracilentum, T. oliganthum, and T. palmeri) that have a high degree of genetic and morphological similarity. The similar morphology of the leaves, inflorescences, and other parts has caused numerous misidentifications as well as disagreements over the delimitation of the taxa. Thus, the primary objective of this study is to revise the taxonomy of the T. gracilentum species complex. The geographic range of the species complex also lends itself to a biogeographic study. Several taxa within the species complex span from the North American mainland to islands off the coast, particularly the California Channel Islands. The Channel Islands are much closer to the mainland than the most well-studied island systems, which provides a good opportunity for testing the equilibrium model of island biogeography in a low-isolation island system. This model predicts that the rate of speciation increases with distance from the mainland, so for the T. gracilentum species complex the model would predict a higher level of morphological differentiation from the mainland in the organisms from the islands that are farther from the shore. The null hypothesis is that all organisms within the species complex are members of the same species. To test the hypothesis, morphological data was collected from herbarium specimens, and the data are being analyzed in R with principal component analysis (PCA) and cluster analyses (CAs). Delimitation decisions will be made according to the phenetic species concept. The equilibrium model of island biogeography will be tested with a multivariate analysis of variance (MANOVA). Preliminary results do not support the null hypothesis and suggest that recognition of 6-7 taxa within the species complex would be appropriate. The results also suggest that there may be some divergence in morphology in island organisms versus mainland organisms, and that there may be differences among organisms from different islands.


1 - Miami University, Biology Dept, 700 E. High St., Oxford, OH, 45056, United States
2 - Miami University, Department Of Biology, Dept Of Biology, Miami University, 100 Bishop Circle, Rm. 79 Upham Hal, Oxford, OH, 45056, United States

Keywords:
Trifolium
western United States
Channel Islands.

Presentation Type: Poster This poster will be presented at 5:30 pm. The Poster Session runs from 5:30 pm to 7:00 pm. Posters with odd poster numbers are presented at 5:30 pm, and posters with even poster numbers are presented at 6:15 pm.
Number: PSY017
Abstract ID:669
Candidate for Awards:None


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