Date of Award
Doctor of Philosophy (PhD)
Lytton J. Musselman
Rebecca D. Bray
Piero G. Delprete
Tatyana A. Lobova
Chiococceae are a monophyletic assemblage of morphologically very diverse groups of plants ranging in habit from subshrubs to shrubs to tall trees exhibiting an astonishing variation in shapes and sizes of corolla, and kinds of fruits and seeds. They are primarily distributed in the Neotropics but also occur in the West Pacific islands; thus exhibiting amphi-Pacific tropical disjunction. This study addresses the phylogenetic relationships and biogeography of the Chiococceae using molecular DNA sequence data, and presents novel data on the tribal and generic delimitations, intergeneric relationships, and the origin and dispersal of this group.
In the most recent tribal delimitations within subfamily Cinchonoideae, Strumpfia, a monotypic genus with historically uncertain tribal affiliation, is included in tribe Chiococceae despite distinctly differing morphologically from the rest of the genera in Chiococceae. Based on intertribal genetic divergences in the subfamily Cinchonoideae, analyzed in this study, coupled with morphological and palynological data, is transferred to a new monotypic tribe Strumpfieae; concurrently tribe Chiococceae is re-delimited to include 29 genera.
This study presents the most comprehensive molecular phylogeny, to date, of the Chiococceae that includes 126 species and 27 genera and enables better understanding of taxonomic affinities and evolutionary relationships within the tribe. Based on the phylogenies generated by analyzing molecular sequence data of two nuclear (ETS, ITS) and two chloroplast (petD, trnL-F) regions using Bayesian inference and maximum parsimony frameworks, a total of nine new taxonomic changes are proposed- generic recognition for five new genera, and synonymization and new combinations for three genera ( Ceuthocarpus, Morierina, and Phyllacanthus ) and two species of Chiococca (C. plowmanii and C. naiguatensis).
Historical events of origin, diversification and disjunction in Chiococceae were inferred with the help of molecular dating analysis using BEAST and ancestral area reconstruction using S-DIVA and BBM. Results indicate that tribe Chiococceae originated in Mexico in the Eocene and through subsequent dispersal, vicariance, and extinction events dispersed to the current distribution in the Neotropics. Multiple dispersal events to the Caribbean and back to Mexico and Central America are inferred. Two Mid-Miocene long-distance dispersal events from the Greater Antilles, one to the New Caledonia and another to other islands of the West Pacific, resulted in the amphi-Pacific tropical disjunction in the Chiococceae.
Paudyal, Sushil K..
"Molecular Phylogenetics and Historical Biogeography of the Tribe Chiococceae (Rubiaceae)"
(2015). Doctor of Philosophy (PhD), dissertation, Biological Sciences, Old Dominion University, DOI: 10.25777/v377-hr74