Phylogenetic systematics of Cunoniaceae (Oxalidales) with an emphasis on species-groups and inflorescence evolution in Weinmannia and related genera.

摘要

This thesis contributes new data to our understanding of the phylogenetics, morphology, and biogeography of the angiosperm plant family Cunoniaceae (Oxalidales) and relatives. Herbarium and live collections were used to gather morphological data. DNA sequences come from two chloroplast loci, trnL-trnF and rbcL. The first paper treats the morphology, inflorescence architecture and cladistics of Weinmannia, the largest genus with ca. 150 species among the Americas, Madagascar and neighboring islands, Malesia, and islands of the South Pacific. Taxonomic sections are generally endemic to a major geographic region, with the exception of section Weinmannia, with ca. 70 species in the Americas and two species from the Mascarene Islands (W. Indian Ocean), which are of recent volcanic origin. Positional homologies are used to code inflorescence characters for cladistics, and inferring architectural evolution based on these characters is a macroevolutionary study in heterotopy, or evolution of position, which has largely been overlooked in favor of heterochrony. These inflorescence characters are used in another paper to classify and identify Weinmannia species-groups in Madagascar. A companion paper treats sixteen species, of which six are described, from a reserve in northern Madagascar. The following paper is a family-level phylogenetic analysis using DNA sequences, morphology and anatomy. A total of 26 genera and approximately 300 species comprise a monophyletic Cunoniaceae, including the often excluded genera Bauera, Davidsonia and Eucryphia; while Brunellia is closely related but not part of the family. Aphanopetalum is not closely related and belongs in Saxifragales. Twenty genera are placed among six tribes, Cunonieae, Codieae, Geissoieae, Caldcluvieae trib. nov., Schizomerieae trib. nov., and Spiraeanthemeae, and six poorly resolved genera are not placed into any formally named group. Among outgroups, the Australian endemic family Tremandraceae is nested within Elaeocarpaceae. Genera from South America and Africa are not most closely related genera, but to groups from the Australasia-Pacific region, suggesting that continental disjunctions reflect Gondwanan vicariance. The final paper is a systematic synopsis with sections on: (1) Phylogenetics, and Classification, (2) Morphology and Anatomy, (3) Ecology and Distribution, (4) Fossil Record, (5) Economic Botany, (6) Endangered Species, and (7) Taxonomic Key and Descriptions.