Basal cactus phylogeny: implications of Pereskia (Cactaceae) paraphyly for the transition to the cactus life form

The cacti are well-known desert plants, widely recognized by their specialized growth form and essentially leafless condition. Pereskia, a group of 17 species with regular leaf development and function, is generally viewed as representing the "ancestral cactus," although its placement with...

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Published inAmerican journal of botany Vol. 92; no. 7; pp. 1177 - 1188
Main Authors Edwards, Erika J, Nyffeler, Reto, Donoghue, Michael J
Format Journal Article
LanguageEnglish
Published United States Botanical Soc America 01.07.2005
Botanical Society of America
Botanical Society of America, Inc
Subjects
bark
biogeography
Botanical gardens
Cactaceae
Cactus
Datasets
DNA
Evolution
genes
Genetics
inferior ovary
internal transcribed spacers
introns
molecular systematics
nuclear genome
nucleotide sequences
Ovaries
Pereskia
photosynthesis
Phylogeny
phytochrome C
phytogeography
plant morphology
plant taxonomy
Plants
plastid DNA
stem-based photosynthesis
Stomata
Systematics
Taxa
taxonomic revisions
Taxonomy
trnK/matK
We they distinction
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Summary:The cacti are well-known desert plants, widely recognized by their specialized growth form and essentially leafless condition. Pereskia, a group of 17 species with regular leaf development and function, is generally viewed as representing the "ancestral cactus," although its placement within Cactaceae has remained uncertain. Here we present a new hypothesis of phylogenetic relationships at the base of the Cactaceae, inferred from DNA sequence data from five gene regions representing all three plant genomes. Our data support a basal split in Cactaceae between a clade of eight Pereskia species, centered around the Caribbean basin, and all other cacti. Two other Pereskia clades, distributed mostly in the southern half of South America, are part of a major clade comprising Maihuenia plus Cactoideae, and Opuntioideae. This result highlights several events in the early evolution of the cacti. First, during the transition to stem-based photosynthesis, the evolution of stem stomata and delayed bark formation preceded the evolution of the stem cortex into a specialized photosynthetic tissue system. Second, the basal split in cacti separates a northern from an initially southern cactus clade, and the major cactus lineages probably originated in southern or west-central South America.
Bibliography:http://www.amjbot.org/
The authors thank Wendy Applequist, Miriam Diaz, Urs Eggli, Beat Leuenberger, the Desert Botanical Garden (Phoenix, Arizona USA), the Berlin Botanical Garden (Berlin‐Dahlem, Germany), the Sukkulenten‐Sammlung (Zü rich, Switzerland), and the Jardín Botánico Nacional (Santo Domingo, Dominican Republic) for tissue or DNA samples and/or logistical support in the field. We owe special thanks to Dianella Howarth and Philippe Reuge for their help and advice in the lab and to Casey Dunn, Nico Cellinese, and the Donoghue Lab for helpful discussions. Beat Leuenberger and two anonymous reviewers provided comments that greatly improved this manuscript. This work was funded in part from a National Science Foundation Graduate Research Fellowship and a Deland Award for Student Research from the Arnold Arboretum of Harvard University to E. J. E, and by a grant from the Swiss National Science Foundation (823A‐056624) to R. N.
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ISSN:0002-9122
1537-2197
DOI:10.3732/ajb.92.7.1177