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Abstract Detail


Baker, Marc A. [1], Cloud-Hughes, Michelle [2], Majure, Lucas Charles [3].

The roles of morphological and molecular methods with regard to intraspecific circumscription in Cactaceae.

Intraspecific and interspecific taxonomy in Cactaceae is often complicated by fragmented geography, polyploidy, hybridization, apomixis, homoplasy, and overlapping character states. Taxonomic problems are further exacerbated by the naming of taxa from very few specimens without a statistical assessment of the variation of key characters and how they correlate with geography, cytology, and ecology. Molecular techniques have been successful in elucidating the evolutionary relationships of genera and species complexes in Cactaceae through phylogenetics and population genetics but have contributed little to the stabilization of taxonomy at the intraspecific level. To maintain a practical taxonomy for vascular plants, interspecific and intraspecific taxa should be defined by characteristics that are assessable from populations in the field. The most practical assessments include morphological characteristics that can be used to create taxonomic keys and that do not require laboratory techniques to interpret. The primary objectives for taxonomic studies should be the assessment of the range of variation within a particular taxon and to assign names in a logical and statistically-defendable manner. Much of the error inherent to environmental variation and sampling can be overcome with large sample sizes, although this can be very difficult for some taxa. Especially for those that may have fewer morphological characters on which to base those assessments, a common problem encountered in certain groups of cacti (e.g., Opuntia). While DNA studies are necessary for determining evolutionary relationships among taxa, and likewise reliably determining the origin of many polyploid taxa (i.e., putative parental discovery), morphological studies are still the most practical means of reliable field identification. A combination of cytological, morphological and DNA studies provides the most complete picture for taxon delimitation, especially for problematic taxa, as will be discussed using studies in Coryphantha, Cylindropuntia, Echinocereus, and Opuntia.

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1 - Arizona State University, School of Life Sciences, PO Box 874501, Tempe, AZ, 85287, USA
2 - Desert Solitaire Botany and Ecological Restoration, San Diego, CA, 92103, USA
3 - Desert Botanical Garden, Research, Conservation, and Collections, 1201 N. Galvin Parkway, Phoenix, AZ, 85008, USA

molecular systematics

Presentation Type: Oral Paper
Session: 14, Systematics I: Basal Dicots, Monocots & Rosids
Location: Sundance 1/Omni Hotel
Date: Monday, June 26th, 2017
Time: 4:15 PM
Number: 14012
Abstract ID:261
Candidate for Awards:None

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