Systematics/Phytogeography / Taxonomie/ Section
Swenson, Ulf , Richardson, James , Bartish, Igor .
Multi-gene phylogeny of the pantropical subfamily Chrysophylloideae (Sapotaceae): evidence of generic polyphyly and extensive morphological homoplasy.
We present a molecular phylogeny of 26 out of 28 currently accepted genera in the subfamily Chrysophylloideae (Sapotaceae) using parsimony jackknifing and Bayesian inference. A data matrix of 8984 characters was obtained from DNA sequences of seven loci from the chloroplast, two loci from the nucleus, gaps coded as binary characters, and morphology. Our phylogenetic reconstruction suggests that Chrysophyllum, Pouteria, and Pradosia, as well as some sections within Chrysophyllum and Pouteria, are all polyphyletic. These taxa were previously described largely on the basis of unique combinations of states for a set of key morphological characters. Mapping some of these characters onto the molecular tree indicate that pollen data conforms well to the recovered topology and that the symplesiomorphic flower in the subfamily most probably was 5-merous, had stamens inserted in the tube orifice, staminodes, seeds with foliaceous cotyledons, exserted radicle, and an endosperm. These characters have subsequently been lost multiple times and cannot be used as synapomorphies to support broad generic concepts. There is no evidence that lost features in this subfamily re-evolve, an important result for phylogenetic estimation using morphology. Despite the high degree of homoplasy some well-defined clades can be described on the basis of alternative character state combinations. Also, many of these well-supported clades appear to be restricted to particular geographical areas, e.g., all taxa in Australasia form a monophyletic group. Hence, we suggest that the segregate genera Aningeria, Malacantha, and Martiusella may ultimately be resurrected, and probably also Donella and Gambeya, but their circumscriptions are still unclear. One species, Chrysophyllum cuneifolium, may have originated from a hybridization event between continents where the maternal genome (cpDNA) comes from South America and the nuclear genome comes from Africa.
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1 - Swedish Museum of Natural History, Department of Phanerogamic Botany, P.O. Box 50007, Stockholm, SE-104 05, Sweden
2 - Royal Botanical Garden Edinburgh, 20a Inverleith Row, Edinburgh, EH3 5LR, United Kingdom
3 - Université de Rennes, Ecosystèmes - Biodiversité - Evolution, 263 Avenue du Général Leclerc, Rennes, 35042, France
Presentation Type: Oral Paper:Papers for Sections
Location: Room 3/Woodward
Date: Monday, July 28th, 2008
Time: 2:30 PM