title: Cryptic speciation in allotetraploids: Lessons from the Botrychium matricariifolium complex.
abstract: Cryptic species are a challenge for botanists and taxonomists. To improve species delineation in the genus Botrychium (Ophioglossaceae), which includes multiple instances of allotetraploid speciation, we examined a cryptic species complex using genetics and morphology.
  
  
  
  We sampled species in the B. matricariifolium complex, concentrating on the Upper Peninsula of Michigan and including multiple proposed morphospecies. We analyzed over 1500 samples using 10 enzyme systems, measured 42 quantitative and qualitative morphological characters for over 650 individuals, and analyzed 145 samples using AFLPs. We tested for diagnostic enzymes in the morphospecies and calculated the correlation between morphological and genetic distances to determine whether putatively distinct morphotypes warrant taxonomic recognition.
  
  
  
  Allozyme allelic variation corresponded loosely to some morphotypes of B. matricariifolium, but with lower genetic distinction among them than found between B. matricariifolium and B. michiganense. Botrychium michiganense contains unique alleles, indicating a different hybrid origin from that of B. matricariifolium and supporting its status as a genetically distinct species.
  
  
  
  We showed that B. acuminatum morphology and genetics are accommodated taxonomically within B. matricariifolium; B. matricariifolium and B. michiganense likely represent hybridization events between related species; and morphotypes within B. matricariifolium likely represent repeated hybridization events between the same two parental species. These hybridizations have resulted in the array of morphotypes observed by field botanists. By helping to identify diagnostic morphological characters, genetic analyses also help us understand and resolve morphological variation observed in the field.
authors.affiliation: Chicago Botanic Garden, Department of Plant Biology and Conservation, 1000 Lake Cook Road, Glencoe, Illinois 60022 USA ewwilli@gmail.com.
authors.forename: Evelyn W
authors.initials: EW
authors.lastname: Williams
authors.affiliation: Iowa State University, Department of Ecology, Evolution, and Organismal Biology, 253 Bessey Hall, Ames, Iowa 50011 USA.
authors.forename: Donald R
authors.initials: DR
authors.lastname: Farrar
authors.affiliation: Tamarack Studios, P. O. Box 453, Manistique, Michigan 49854-0453 USA.
authors.forename: Don
authors.initials: D
authors.lastname: Henson
mesh_terms: D000483:Alleles; D054458:Amplified Fragment Length Polymorphism Analysis; D004171:Diploidy; D049810:Genetic Speciation; D005843:Geography; D006824:Hybridization, Genetic; D008954:Models, Biological; D011123:Polyploidy; D025341:Principal Component Analysis; D013048:Specimen Handling; D064028:Tracheophyta / Q000033:anatomy & histology / Q000235:genetics*; D014481:United States
keywords: Botrychium matricariifolium; Ophioglossaceae; allozymes; cryptic species; ferns; polyploidy; speciation