Phylogeny, classification, and morphological diversification in Menispermaceae (moonseed family).

摘要

Menispermaceae are an angiosperm family of dioecious, predominantly climbing plants, with about 72 genera and ca. 520 species that are primarily distributed in the tropical regions of the world. Menispermaceae are placed within the order Ranunculales where they share a sister relationship with the Berberidaceae + Ranunculaceae clade. The inconspicuous, unisexual flowers that characterize the family were early on acknowledged of little value for infrafamilial classification. On the other hand, characters of the fruit, specifically characters of the endocarp and seed have been considered traditionally taxonomically important, and have therefore been used extensively in infrafamilial classifications. However, different weights attached by different authors to these same characters have resulted in the recognition of not only heterogeneous assemblages, but also contentious suprageneric classifications.;This dissertation comprises the following three chapters: 1, Molecular phylogeny of the moonseed family (Menispermaceae): Implications for morphological diversification; 2, Seed diversity in Menispermaceae: Developmental anatomy and insights into the origin of the condyle; 3, A revised infrafamilial classification of the Menispermaceae based on the chloroplast gene ndhF and morphological evidence.;1. The phylogeny of Menispermaceae was reconstructed using DNA sequences of 88 species representing 49 of the 72 genera of all eight traditionally recognized tribes. The resulting phylogeny is partially congruent with the widely used classification of the family. Of the eight tribes usually recognized, four were found to be monophyletic, while the others are either para- or polyphyletic. Tracing of major morphological characters onto the phylogeny indicates that the crescent shaped seed is derived from a straight seed, the arborescent habit has arisen several times, endosperm has been lost many times, but unicarpellate flowers evolved only once. Morphological synapomorphies in Menispermaceae include the presence of a condyle, a large embryo, and a druplet.;2. The condyle has been considered historically an important taxonomic feature in the Menispermaceae. To understand the morphological basis of the condyle, I undertook a developmental study of carpels and fruits in selected lineages in Menispermaceae and related families in the Ranunculales. My results indicate that the condyle is the outcome of differential development of the adaxial portion of the ovary wall. Two general types of condyles are described: 1) Calycocarpum type, where a broad region of the middle zone of the adaxial pericarp proliferates resulting in a convex condyle, the anatropous ovules develop into concave-convex seeds; 2) Menispermum type, where proliferation occurs in the inner zone of the pericarp. Unequal growth in the lateral middle zone results in laterally compressed condyles and the hemianatropous ovules develop into curved seeds. Further variation in condyle shapes in the second group is caused by differential development of areas above and below the funicle. The two types of condyles described here are potential synapomorphies for the two subfamilies being recognized in the Menispermaceae.;3. A new suprageneric classification based on a phylogenetic analysis of DNA sequences of the ndhF chloroplast gene is presented. Clades are recognized at the subfamily and tribal level. Named clades are well-supported and diagnosed by morphological synapomorphies. Genera not sampled in this study are assigned provisionally to the recognized tribes based on morphological characters.