Date of Award

Spring 5-2015

Degree Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Biological Sciences

Committee Chair

Mac H. Alford

Committee Chair Department

Biological Sciences

Committee Member 2

Kenneth J. Curry

Committee Member 2 Department

Biological Sciences

Committee Member 3

Micheal A. Davis

Committee Member 3 Department

Biological Sciences

Committee Member 4

Brian R. Kreiser

Committee Member 4 Department

Biological Sciences

Committee Member 5

Carl A. Reese

Committee Member 5 Department

Geography and Geology

Abstract

The flowering plant family Samydaceae was recently reinstated to include 14 genera and about 256 species of tropical trees and shrubs. Preliminary analyses of relationships in the family, however, indicated that the largest genus in the family, Casearia, is not monophyletic and that several smaller groups are probably misplaced. In order to affirm or refute those hypotheses, additional DNA sequence data with broader taxon sampling from the Old World were gathered for phylogenetic analysis. In particular, rapidly evolving plastid (matK, ndhF, psbA-trnH, trnL, and trnL-F) and nuclear (EMB2765 and GBSSI) DNA regions were sampled for characters. Four of these regions (matK, ndhF, EMB2765, GBSSI) could be confidently aligned across the family, and phylogenetic inferences were drawn from parsimony, likelihood, and Bayesian analyses primarily of these data. The results affirm the monophyly of Samydaceae and consistently recover four major clades, which are here circumscribed as four tribes, namely Lunanieae, Ryanieae, Samydeae, and Tetrathylacieae. The results also affirm that Casearia is not monophyletic. Rather, several small genera (Samyda, Laetia sensu stricto, Hecatostemon, and Zuelania) are nested within it. One previously recognized genus, Piparea, which is more closely related to Ryania, and Trichostephanus, should be reinstated. A key to the newly circumscribed tribes and genera is provided.

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