title: Geographic distribution and taxonomic circumscription of populations within Coryphantha section Robustispina (Cactaceae).
abstract: OBJECTIVE
  Taxonomic circumscription of subspecific taxa within Coryphantha robustispina was evaluated with morphological data and microsatellites. This study was the first to compare adequately sampled morphological and DNA analyses at the population level in the Cactaceae. This comparison was important to test reliability of both methods and to gain a better understanding of phytogeography, evolution, and systematics of the species, knowledge that could prove useful for other taxa as well. Populations of C. robustispina subsp. robustispina are listed as endangered by the U. S. Fish and Wildlife Service. Our primary goal was to explore correlations among geographical distribution, morphology, and genetics of selected populations throughout the range of the species and the outgroup, C. poselgeriana. •
  
  
  METHODS
  Stem characters were measured for 638 individuals among 16 populations. Flower characters were measured for 180 individuals among 12 populations. Ten microsatellite DNA loci were isolated and characterized for 204 individuals among 13 populations. Data were analyzed using various multivariate analyses. •
  
  
  RESULTS
  Our results indicated that, within Coryphantha robustispina, there were three morphologically, genetically, and geographically coherent groups represented by the names C. robustispina subsp. robustispina, C. robustispina subsp. uncinata, and C. robustispina subsp. scheeri. For most analyses, distinctions among the three groups were primarily not as great as those between any one of them and the outgroup. •
  
  
  CONCLUSIONS
  Results suggested that the three subspecific taxa within Coryphantha robustispina are good subspecies but should not be elevated to species rank. The closely aligned results between morphology and microsatellite data support the design and utility of both methods.
authors: Arizona State University, Main Campus, College of Liberal Arts and Sciences, School of Life Sciences, P. O. Box 874501, Tempe, AZ 85287-4501, USA. mbaker6@asu.edu
authors: Marc A
authors: MA
authors: Baker
authors: Charles A
authors: CA
authors: Butterworth
mesh_terms: D029421:Cactaceae / Q000145:classification / Q000235:genetics* / Q000502:physiology*; D018744:DNA, Plant / Q000235:genetics; D004268:DNA-Binding Proteins; D003710:Demography; D029968:Escherichia coli Proteins; D008800:Mexico; D018895:Microsatellite Repeats / Q000235:genetics; D025341:Principal Component Analysis; D013045:Species Specificity; D014481:United States
chemical_list: D018744:DNA, Plant; D004268:DNA-Binding Proteins; D029968:Escherichia coli Proteins; C476430:SSB protein, E coli
keywords: Cactaceae; Coryphantha; Coryphantha robustispina; PCA; UPGMA; endangered species; microsatellites; morphological analysis; taxonomic circumscription